[Net] Add Java version of NetworkTrafficAnnotationTag

This class is very similar to the C++ NetworkTrafficAnnotationTag
class. It requires the same kind of documentation, in as a text
protobuf.

As a proof-of-concept, update EndpointFetcher methods to take a
NetworkTrafficAnnotationTag argument, and plumb it down to C++. For now,
use NO_TRAFFIC_ANNOTATION_YET in callers.

Since auditor.py doesn't scan Java files yet, the contents of the
annotations doesn't need to be valid for now.

Bug: 1231780, 995852
Change-Id: I798a99adfd9d2d2afee537b78d379e9f05b49a9a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3045770
Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Commit-Queue: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Cr-Commit-Position: refs/heads/main@{#917776}

chrome/android/features/tab_ui/BUILD.gn

@@ -233,6 +233,7 @@ android_library("java") {
     "//components/site_engagement/content/android:java",
     "//content/public/android:content_java",
     "//content/public/android:content_java_resources",
+    "//net/android:net_java",
     "//third_party/android_deps:android_support_v7_appcompat_java",
     "//third_party/android_deps:material_design_java",
     "//third_party/androidx:androidx_annotation_annotation_java",

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabSuggestionsServerFetcher.java

@@ -21,6 +21,7 @@ import org.chromium.chrome.browser.profiles.Profile;
 import org.chromium.chrome.browser.signin.services.IdentityServicesProvider;
 import org.chromium.chrome.browser.tasks.tab_management.TabUiFeatureUtilities;
 import org.chromium.components.signin.identitymanager.ConsentLevel;
+import org.chromium.net.NetworkTrafficAnnotationTag;
 
 import java.util.Collections;
 import java.util.LinkedList;
@@ -78,12 +79,14 @@ public class TabSuggestionsServerFetcher implements TabSuggestionsFetcher {
                     return;
                 }
             }
+            // TODO(crbug.com/995852): Replace NO_TRAFFIC_ANNOTATION_YET with a real traffic
+            // annotation.
             EndpointFetcher.fetchUsingChromeAPIKey(res
                     -> { fetchCallback(res, callback, tabContext); },
                     mProfileForTesting == null ? Profile.getLastUsedRegularProfile()
                                                : mProfileForTesting,
                     ENDPOINT, METHOD, CONTENT_TYPE, getTabContextJson(tabContext), TIMEOUT_MS,
-                    new String[] {});
+                    new String[] {}, NetworkTrafficAnnotationTag.NO_TRAFFIC_ANNOTATION_YET);
         } catch (JSONException e) {
             // Soft failure for now so we don't crash the app and fall back on client side
             // providers.

chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediatorUnitTest.java

@@ -3162,7 +3162,7 @@ public class TabListMediatorUnitTest {
                     .when(mEndpointFetcherJniMock)
                     .nativeFetchOAuth(any(Profile.class), anyString(), contains(entry.getKey()),
                             anyString(), anyString(), any(String[].class), anyString(), anyLong(),
-                            any(Callback.class));
+                            anyInt(), any(Callback.class));
         }
     }
 

chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/suggestions/TabSuggestionsServerFetcherUnitTest.java

@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.tasks.tab_management.suggestions;
 
 import static org.hamcrest.Matchers.is;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.doAnswer;
@@ -115,21 +116,21 @@ public class TabSuggestionsServerFetcherUnitTest {
         doAnswer(new Answer<Void>() {
             @Override
             public Void answer(InvocationOnMock invocation) {
-                Callback callback = (Callback) invocation.getArguments()[7];
+                Callback callback = (Callback) invocation.getArguments()[8];
                 callback.onResult(new EndpointResponse(response));
                 return null;
             }
         })
                 .when(mEndpointFetcherJniMock)
                 .nativeFetchChromeAPIKey(any(Profile.class), anyString(), anyString(), anyString(),
-                        anyString(), anyLong(), any(String[].class), any(Callback.class));
+                        anyString(), anyLong(), any(String[].class), anyInt(), any(Callback.class));
     }
 
     private void verifyEndpointArguments() {
         verify(mEndpointFetcherJniMock)
                 .nativeFetchChromeAPIKey(eq(mProfile), eq(EXPECTED_ENDPOINT_URL),
                         eq(EXPECTED_METHOD), eq(EXPECTED_CONTENT_TYPE), any(String.class),
-                        eq(EXPECTED_TIMEOUT), any(String[].class), any(Callback.class));
+                        eq(EXPECTED_TIMEOUT), any(String[].class), anyInt(), any(Callback.class));
     }
 
     @Test

chrome/android/javatests/src/org/chromium/chrome/browser/tab/state/ShoppingPersistedTabDataTestUtils.java

@@ -324,7 +324,7 @@ public abstract class ShoppingPersistedTabDataTestUtils {
     static void verifyEndpointFetcherCalled(EndpointFetcher.Natives endpointFetcher, int numTimes) {
         verify(endpointFetcher, times(numTimes))
                 .nativeFetchChromeAPIKey(any(Profile.class), anyString(), anyString(), anyString(),
-                        anyString(), anyLong(), any(String[].class), any(Callback.class));
+                        anyString(), anyLong(), any(String[].class), anyInt(), any(Callback.class));
     }
 
     static void verifyPriceTrackingOptimizationTypeCalled(
@@ -342,4 +342,4 @@ public abstract class ShoppingPersistedTabDataTestUtils {
                         eq(HintsProto.OptimizationType.PRICE_TRACKING.getNumber()),
                         any(OptimizationGuideCallback.class));
     }
-}
+}

chrome/android/javatests/src/org/chromium/chrome/browser/tab/state/StorePersistedTabDataTest.java

@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.tab.state;
 
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.doAnswer;
@@ -314,14 +315,14 @@ public class StorePersistedTabDataTest {
         doAnswer(new Answer<Void>() {
             @Override
             public Void answer(InvocationOnMock invocation) {
-                Callback callback = (Callback) invocation.getArguments()[8];
+                Callback callback = (Callback) invocation.getArguments()[9];
                 callback.onResult(new EndpointResponse(response));
                 return null;
             }
         })
                 .when(mEndpointFetcherJniMock)
                 .nativeFetchOAuth(any(Profile.class), anyString(), anyString(), anyString(),
-                        anyString(), any(String[].class), anyString(), anyLong(),
+                        anyString(), any(String[].class), anyString(), anyLong(), anyInt(),
                         any(Callback.class));
     }
 }

chrome/browser/commerce/subscriptions/android/java/src/org/chromium/chrome/browser/subscriptions/CommerceSubscriptionsServiceProxy.java

@@ -12,6 +12,7 @@ import org.chromium.base.Callback;
 import org.chromium.base.Log;
 import org.chromium.chrome.browser.endpoint_fetcher.EndpointFetcher;
 import org.chromium.chrome.browser.profiles.Profile;
+import org.chromium.net.NetworkTrafficAnnotationTag;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -75,6 +76,8 @@ public final class CommerceSubscriptionsServiceProxy {
      */
     public void get(@CommerceSubscription.CommerceSubscriptionType String type,
             Callback<List<CommerceSubscription>> callback) {
+        // TODO(crbug.com/995852): Replace NO_TRAFFIC_ANNOTATION_YET with a real traffic
+        // annotation.
         EndpointFetcher.fetchUsingOAuth(
                 (response)
                         -> {
@@ -84,10 +87,12 @@ public final class CommerceSubscriptionsServiceProxy {
                 CommerceSubscriptionsServiceConfig.SUBSCRIPTIONS_SERVICE_BASE_URL.getValue()
                         + String.format(GET_SUBSCRIPTIONS_QUERY_PARAMS_TEMPLATE, type),
                 GET_HTTPS_METHOD, CONTENT_TYPE, OAUTH_SCOPE, EMPTY_POST_DATA,
-                HTTPS_REQUEST_TIMEOUT_MS);
+                HTTPS_REQUEST_TIMEOUT_MS, NetworkTrafficAnnotationTag.NO_TRAFFIC_ANNOTATION_YET);
     }
 
     private void manageSubscriptions(JSONObject requestPayload, Callback<Boolean> callback) {
+        // TODO(crbug.com/995852): Replace NO_TRAFFIC_ANNOTATION_YET with a real traffic
+        // annotation.
         EndpointFetcher.fetchUsingOAuth(
                 (response)
                         -> {
@@ -97,7 +102,7 @@ public final class CommerceSubscriptionsServiceProxy {
                 mProfile, OAUTH_NAME,
                 CommerceSubscriptionsServiceConfig.SUBSCRIPTIONS_SERVICE_BASE_URL.getValue(),
                 POST_HTTPS_METHOD, CONTENT_TYPE, OAUTH_SCOPE, requestPayload.toString(),
-                HTTPS_REQUEST_TIMEOUT_MS);
+                HTTPS_REQUEST_TIMEOUT_MS, NetworkTrafficAnnotationTag.NO_TRAFFIC_ANNOTATION_YET);
     }
 
     private boolean didManageSubscriptionCallSucceed(String responseString) {

chrome/browser/commerce/subscriptions/test/android/java/src/org/chromium/chrome/browser/subscriptions/CommerceSubscriptionsServiceProxyUnitTest.java

@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.subscriptions;
 
 import static org.junit.Assert.assertNotNull;
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doAnswer;
@@ -239,14 +240,14 @@ public class CommerceSubscriptionsServiceProxyUnitTest {
         verify(mEndpointFetcherJniMock, times(numTimes))
                 .nativeFetchOAuth(any(Profile.class), any(String.class), eq(expectedUrl),
                         eq(expectedMethod), eq(EXPECTED_CONTENT_TYPE), eq(EXPECTED_OAUTH_SCOPES),
-                        eq(expectedPayload), anyLong(), any(Callback.class));
+                        eq(expectedPayload), anyLong(), anyInt(), any(Callback.class));
     }
 
     private void mockEndpointResponse(String response) {
         doAnswer(new Answer<Void>() {
             @Override
             public Void answer(InvocationOnMock invocation) {
-                Callback callback = (Callback) invocation.getArguments()[8];
+                Callback callback = (Callback) invocation.getArguments()[9];
                 callback.onResult(new EndpointResponse(response));
                 return null;
             }
@@ -254,6 +255,6 @@ public class CommerceSubscriptionsServiceProxyUnitTest {
                 .when(mEndpointFetcherJniMock)
                 .nativeFetchOAuth(any(Profile.class), any(String.class), any(String.class),
                         any(String.class), eq(EXPECTED_CONTENT_TYPE), eq(EXPECTED_OAUTH_SCOPES),
-                        any(String.class), anyLong(), any(Callback.class));
+                        any(String.class), anyLong(), anyInt(), any(Callback.class));
     }
 }

chrome/browser/endpoint_fetcher/BUILD.gn

@@ -9,6 +9,7 @@ android_library("java") {
     ":jni_headers",
     "//base:base_java",
     "//chrome/browser/profiles/android:java",
+    "//net/android:net_java",
     "//third_party/androidx:androidx_annotation_annotation_java",
   ]
   sources = [

chrome/browser/endpoint_fetcher/endpoint_fetcher.cc

@@ -317,6 +317,7 @@ static void JNI_EndpointFetcher_NativeFetchOAuth(
     const base::android::JavaParamRef<jobjectArray>& jscopes,
     const base::android::JavaParamRef<jstring>& jpost_data,
     jlong jtimeout,
+    jint jannotation_hash_code,
     const base::android::JavaParamRef<jobject>& jcallback) {
   std::vector<std::string> scopes;
   base::android::AppendJavaStringArrayToStringVector(env, jscopes, &scopes);
@@ -327,9 +328,8 @@ static void JNI_EndpointFetcher_NativeFetchOAuth(
       base::android::ConvertJavaStringToUTF8(env, jhttps_method),
       base::android::ConvertJavaStringToUTF8(env, jcontent_type), scopes,
       jtimeout, base::android::ConvertJavaStringToUTF8(env, jpost_data),
-      // TODO(crbug.com/995852) Create a traffic annotation tag and configure it
-      // as part of the EndpointFetcher call over JNI.
-      NO_TRAFFIC_ANNOTATION_YET);
+      net::NetworkTrafficAnnotationTag::FromJavaAnnotation(
+          jannotation_hash_code));
   auto* const endpoint_fetcher_ptr = endpoint_fetcher.get();
   endpoint_fetcher_ptr->Fetch(
       base::BindOnce(&OnEndpointFetcherComplete,
@@ -348,6 +348,7 @@ static void JNI_EndpointFetcher_NativeFetchChromeAPIKey(
     const base::android::JavaParamRef<jstring>& jpost_data,
     jlong jtimeout,
     const base::android::JavaParamRef<jobjectArray>& jheaders,
+    jint jannotation_hash_code,
     const base::android::JavaParamRef<jobject>& jcallback) {
   std::vector<std::string> headers;
   base::android::AppendJavaStringArrayToStringVector(env, jheaders, &headers);
@@ -357,7 +358,8 @@ static void JNI_EndpointFetcher_NativeFetchChromeAPIKey(
       base::android::ConvertJavaStringToUTF8(env, jhttps_method),
       base::android::ConvertJavaStringToUTF8(env, jcontent_type), jtimeout,
       base::android::ConvertJavaStringToUTF8(env, jpost_data), headers,
-      NO_TRAFFIC_ANNOTATION_YET);
+      net::NetworkTrafficAnnotationTag::FromJavaAnnotation(
+          jannotation_hash_code));
   auto* const endpoint_fetcher_ptr = endpoint_fetcher.get();
   endpoint_fetcher_ptr->PerformRequest(
       base::BindOnce(&OnEndpointFetcherComplete,
@@ -372,11 +374,13 @@ static void JNI_EndpointFetcher_NativeFetchWithNoAuth(
     JNIEnv* env,
     const base::android::JavaParamRef<jobject>& jprofile,
     const base::android::JavaParamRef<jstring>& jurl,
+    jint jannotation_hash_code,
     const base::android::JavaParamRef<jobject>& jcallback) {
   auto endpoint_fetcher = std::make_unique<EndpointFetcher>(
       ProfileAndroid::FromProfileAndroid(jprofile),
       GURL(base::android::ConvertJavaStringToUTF8(env, jurl)),
-      NO_TRAFFIC_ANNOTATION_YET);
+      net::NetworkTrafficAnnotationTag::FromJavaAnnotation(
+          jannotation_hash_code));
   auto* const endpoint_fetcher_ptr = endpoint_fetcher.get();
   endpoint_fetcher_ptr->PerformRequest(
       base::BindOnce(&OnEndpointFetcherComplete,

chrome/browser/endpoint_fetcher/java/src/org/chromium/chrome/browser/endpoint_fetcher/EndpointFetcher.java

@@ -9,6 +9,7 @@ import androidx.annotation.MainThread;
 import org.chromium.base.Callback;
 import org.chromium.base.annotations.NativeMethods;
 import org.chromium.chrome.browser.profiles.Profile;
+import org.chromium.net.NetworkTrafficAnnotationTag;
 
 /**
  * EndpointFetcher uses native EndpointFetcher to call a HTTPS endpoint and return
@@ -39,11 +40,12 @@ public final class EndpointFetcher {
     @MainThread
     public static void fetchUsingOAuth(Callback<EndpointResponse> callback, Profile profile,
             String oathConsumerName, String url, String httpsMethod, String contentType,
-            String[] scopes, String postData, long timeout) {
+            String[] scopes, String postData, long timeout,
+            NetworkTrafficAnnotationTag annotation) {
         // EndpointFetcher currently does not support incognito mode
         assert !profile.isOffTheRecord();
         EndpointFetcherJni.get().nativeFetchOAuth(profile, oathConsumerName, url, httpsMethod,
-                contentType, scopes, postData, timeout, callback);
+                contentType, scopes, postData, timeout, annotation.getHashCode(), callback);
     }
 
     /**
@@ -61,22 +63,22 @@ public final class EndpointFetcher {
     @MainThread
     public static void fetchUsingChromeAPIKey(Callback<EndpointResponse> callback, Profile profile,
             String url, String httpsMethod, String contentType, String postData, long timeout,
-            String[] headers) {
+            String[] headers, NetworkTrafficAnnotationTag annotation) {
         // EndpointFetcher currently does not support incognito mode
         // assert !profile.isOffTheRecord();
-        EndpointFetcherJni.get().nativeFetchChromeAPIKey(
-                profile, url, httpsMethod, contentType, postData, timeout, headers, callback);
+        EndpointFetcherJni.get().nativeFetchChromeAPIKey(profile, url, httpsMethod, contentType,
+                postData, timeout, headers, annotation.getHashCode(), callback);
     }
 
     @NativeMethods
     public interface Natives {
         void nativeFetchOAuth(Profile profile, String oathConsumerName, String url,
                 String httpsMethod, String contentType, String[] scopes, String postData,
-                long timeout, Callback<EndpointResponse> callback);
+                long timeout, int annotationHashCode, Callback<EndpointResponse> callback);
         void nativeFetchChromeAPIKey(Profile profile, String url, String httpsMethod,
                 String contentType, String postData, long timeout, String[] headers,
+                int annotationHashCode, Callback<EndpointResponse> callback);
+        void nativeFetchWithNoAuth(Profile profile, String url, int annotationHashCode,
                 Callback<EndpointResponse> callback);
-        void nativeFetchWithNoAuth(
-                Profile profile, String url, Callback<EndpointResponse> callback);
     }
 }

chrome/browser/page_annotations/android/BUILD.gn

@@ -23,6 +23,7 @@ android_library("java") {
     "//chrome/browser/flags:java",
     "//chrome/browser/profiles/android:java",
     "//components/embedder_support/android:util_java",
+    "//net/android:net_java",
     "//third_party/androidx:androidx_annotation_annotation_java",
     "//url:gurl_java",
   ]

chrome/browser/page_annotations/android/java/src/org/chromium/chrome/browser/page_annotations/PageAnnotationsServiceProxy.java

@@ -15,6 +15,7 @@ import org.chromium.chrome.browser.endpoint_fetcher.EndpointFetcher;
 import org.chromium.chrome.browser.endpoint_fetcher.EndpointResponse;
 import org.chromium.chrome.browser.profiles.Profile;
 import org.chromium.components.embedder_support.util.UrlUtilities;
+import org.chromium.net.NetworkTrafficAnnotationTag;
 import org.chromium.url.GURL;
 
 import java.util.ArrayList;
@@ -57,6 +58,8 @@ public class PageAnnotationsServiceProxy {
             return;
         }
 
+        // TODO(crbug.com/995852): Replace NO_TRAFFIC_ANNOTATION_YET with a real traffic
+        // annotation.
         EndpointFetcher.fetchUsingChromeAPIKey(
                 (endpointResponse)
                         -> { fetchCallback(endpointResponse, callback); },
@@ -65,7 +68,8 @@ public class PageAnnotationsServiceProxy {
                                 + GET_ANNOTATIONS_QUERY_PARAMS_TEMPLATE,
                         UrlUtilities.escapeQueryParamValue(url.getSpec(), false)),
                 HTTPS_METHOD, CONTENT_TYPE, EMPTY_POST_DATA, TIMEOUT_MS,
-                new String[] {ACCEPT_LANGUAGE_KEY, LocaleUtils.getDefaultLocaleListString()});
+                new String[] {ACCEPT_LANGUAGE_KEY, LocaleUtils.getDefaultLocaleListString()},
+                NetworkTrafficAnnotationTag.NO_TRAFFIC_ANNOTATION_YET);
     }
 
     private void fetchCallback(EndpointResponse response,
@@ -90,4 +94,4 @@ public class PageAnnotationsServiceProxy {
 
         resultCallback.onResult(new SinglePageAnnotationsServiceResponse(annotations));
     }
-}
+}

chrome/browser/page_annotations/test/android/BUILD.gn

@@ -54,6 +54,7 @@ android_library("javatests") {
     "//chrome/browser/page_annotations/android:java",
     "//chrome/browser/profiles/android:java",
     "//chrome/test/android:chrome_java_test_support",
+    "//net/android:net_java",
     "//third_party/androidx:androidx_test_core_java",
     "//third_party/androidx:androidx_test_runner_java",
     "//third_party/junit",

chrome/browser/page_annotations/test/android/java/src/org/chromium/chrome/browser/page_annotations/PageAnnotationsServiceProxyUnitTest.java

@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.page_annotations;
 
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
@@ -168,21 +169,21 @@ public class PageAnnotationsServiceProxyUnitTest {
         verify(mEndpointFetcherJniMock, times(numTimes))
                 .nativeFetchChromeAPIKey(any(Profile.class), eq(expectedUrl), eq(EXPECTED_METHOD),
                         eq(EXPECTED_CONTENT_TYPE), anyString(), anyLong(), eq(expectedHeaders),
-                        any(Callback.class));
+                        anyInt(), any(Callback.class));
     }
 
     private void mockEndpointResponse(String response) {
         doAnswer(new Answer<Void>() {
             @Override
             public Void answer(InvocationOnMock invocation) {
-                Callback callback = (Callback) invocation.getArguments()[7];
+                Callback callback = (Callback) invocation.getArguments()[8];
                 callback.onResult(new EndpointResponse(response));
                 return null;
             }
         })
                 .when(mEndpointFetcherJniMock)
                 .nativeFetchChromeAPIKey(any(Profile.class), anyString(), anyString(), anyString(),
-                        anyString(), anyLong(), any(String[].class), any(Callback.class));
+                        anyString(), anyLong(), any(String[].class), anyInt(), any(Callback.class));
     }
 
     private void verifyAnnotations(List<PageAnnotation> annotations) {

chrome/browser/tab/java/src/org/chromium/chrome/browser/tab/state/DEPS

@@ -2,4 +2,5 @@ include_rules = [
   "+chrome/browser/tabpersistence",
   "+chrome/browser/page_annotations",
   "+components/payments/content/android",
-]
+  "+net/android",
+]

chrome/browser/tab/java/src/org/chromium/chrome/browser/tab/state/StorePersistedTabData.java

@@ -19,6 +19,7 @@ import org.chromium.chrome.browser.endpoint_fetcher.EndpointFetcher;
 import org.chromium.chrome.browser.profiles.Profile;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tab.proto.StorePersistedTabData.StorePersistedTabDataProto;
+import org.chromium.net.NetworkTrafficAnnotationTag;
 
 import java.nio.ByteBuffer;
 import java.util.Locale;
@@ -277,6 +278,8 @@ public class StorePersistedTabData extends PersistedTabData {
      * @param callback {@link Callback} {@link StorePersistedTabData is passed back in}
      */
     public static void from(Tab tab, Callback<StorePersistedTabData> callback) {
+        // TODO(crbug.com/995852): Replace NO_TRAFFIC_ANNOTATION_YET with a real traffic
+        // annotation.
         PersistedTabData.from(tab,
                 (data, storage, id)
                         -> { return new StorePersistedTabData(tab, data, storage, id); },
@@ -290,7 +293,8 @@ public class StorePersistedTabData extends PersistedTabData {
                             },
                             Profile.getLastUsedRegularProfile(), PERSISTED_TAB_DATA_ID,
                             String.format(Locale.US, ENDPOINT, tab.getUrl().getSpec()),
-                            HTTPS_METHOD, CONTENT_TYPE, SCOPES, EMPTY_POST_DATA, TIMEOUT_MS);
+                            HTTPS_METHOD, CONTENT_TYPE, SCOPES, EMPTY_POST_DATA, TIMEOUT_MS,
+                            NetworkTrafficAnnotationTag.NO_TRAFFIC_ANNOTATION_YET);
                 },
                 StorePersistedTabData.class, callback);
     }
@@ -373,4 +377,4 @@ public class StorePersistedTabData extends PersistedTabData {
 
         return Integer.parseInt(sb.toString());
     }
-}
+}

net/android/BUILD.gn

@@ -23,6 +23,7 @@ android_library("net_java") {
     "java/src/org/chromium/net/NetworkActivationRequest.java",
     "java/src/org/chromium/net/NetworkChangeNotifier.java",
     "java/src/org/chromium/net/NetworkChangeNotifierAutoDetect.java",
+    "java/src/org/chromium/net/NetworkTrafficAnnotationTag.java",
     "java/src/org/chromium/net/ProxyBroadcastReceiver.java",
     "java/src/org/chromium/net/ProxyChangeListener.java",
     "java/src/org/chromium/net/RegistrationPolicyAlwaysRegister.java",
@@ -221,7 +222,10 @@ java_cpp_enum("net_android_java_enums_srcjar") {
 }
 
 junit_binary("net_junit_tests") {
-  sources = [ "junit/src/org/chromium/net/HttpNegotiateAuthenticatorTest.java" ]
+  sources = [
+    "junit/src/org/chromium/net/HttpNegotiateAuthenticatorTest.java",
+    "junit/src/org/chromium/net/NetworkTrafficAnnotationTagTest.java",
+  ]
   deps = [
     ":net_java",
     "//base:base_java",

net/android/java/src/org/chromium/net/NetworkTrafficAnnotationTag.java

@@ -0,0 +1,109 @@
+// Copyright 2021 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.net;
+
+import androidx.annotation.VisibleForTesting;
+
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Network Traffic Annotations document the purpose of a particular network request, and its impact
+ * on privacy.
+ *
+ * This documentation is typically meant for system administrators in an enterprise setting. It
+ * should be easy for them to read and understand, and answer the following questions:
+ *
+ *   1. When and why does Chrome make this network request?
+ *   2. Does this network request send any sensitive data?
+ *   3. Where does the request go? (e.g. a Google server, a website the user is viewing...)
+ *   4. How can I disable it if I don't like it?
+ */
+public class NetworkTrafficAnnotationTag {
+    /**
+     * For network requests that aren't documented yet. These should be
+     * accompanied with a TODO with a bug/owner to write their documentation.
+     */
+    public static final NetworkTrafficAnnotationTag NO_TRAFFIC_ANNOTATION_YET =
+            createComplete("undefined", "Nothing here yet.");
+
+    /**
+     * For network requests that don't need an annotation, because they're in an
+     * allowlisted file (see tools/traffic_annotation/auditor/safe_list.txt).
+     */
+    public static final NetworkTrafficAnnotationTag MISSING_TRAFFIC_ANNOTATION =
+            createComplete("undefined", "Function called without traffic annotation.");
+
+    /** For network requests made in tests, don't bother writing documentation. */
+    public static final NetworkTrafficAnnotationTag TRAFFIC_ANNOTATION_FOR_TESTS =
+            createComplete("test", "Traffic annotation for unit, browser and other tests");
+    /**
+     * Create a self-contained tag describing a network request made by Chromium. This is the most
+     * common factory method.
+     *
+     * The C++ equivalent is DefineNetworkTrafficAnnotation().
+     *
+     * @param uniqueId a String that uniquely identifies this annotations across all of Chromium
+     *         source code.
+     * @param proto a text-encoded NetworkTrafficAnnotation protobuf (see
+     *         chrome/browser/privacy/traffic_annotation.proto).
+     */
+    public static NetworkTrafficAnnotationTag createComplete(String uniqueId, String proto) {
+        return new NetworkTrafficAnnotationTag(uniqueId);
+    }
+
+    // TODO(crbug.com/1231780): Add Partial, Completing, Branched-Completing, and
+    // Mutable(?) factory methods.
+
+    /**
+     * At runtime, an annotation tag is just a hashCode. Most of the validation is done on CQ, so
+     * there's no point keeping track of everything at runtime.
+     *
+     * This field is referenced from C++, so don't change it without updating
+     * net/traffic_annotation/network_traffic_annotation.h.
+     */
+    // TODO(crbug.com/1231780): Unlike the C++ version though, the string will still get compiled
+    // into the APK, and get loaded into memory when the constructor is called... Is there a way to
+    // tell Java, "No, I don't actually need this string at runtime"? We should investigate.
+    private final int mHashCode;
+
+    /**
+     * @return the hash code of uniqueId, which uniquely identifies this annotation.
+     */
+    public int getHashCode() {
+        return mHashCode;
+    }
+
+    /**
+     * Constructor for NetworkTrafficAnnotationTag. Consumers of this API should use
+     * CreateComplete() instead.
+     *
+     * @param uniqueId a String that uniquely identifies this annotation across all of Chromium
+     *         source code.
+     */
+    private NetworkTrafficAnnotationTag(String uniqueId) {
+        mHashCode = iterativeHash(uniqueId);
+    }
+
+    /**
+     * Returns the hashcode of a string, as per the recursive_hash() function used in C++ code.
+     *
+     * This is NOT the same as Java's built-in hashCode() function, because we really want to
+     * produce the same hashcode that auditor.py produces.
+     *
+     * @param s the String to calculate the hash on.
+     */
+    @VisibleForTesting
+    static int iterativeHash(String s) {
+        // Multiplying by 31 would cause an overflow if using `int', so use `long' instead.
+        long acc = 0;
+        // Encode the string as UTF-8.
+        byte[] bytes = s.getBytes(StandardCharsets.UTF_8);
+        for (byte b : bytes) {
+            acc = (acc * 31 + b) % 138003713;
+        }
+        // The final result always fits in an `int' thanks to the modulo.
+        return (int) acc;
+    }
+}

net/android/junit/src/org/chromium/net/NetworkTrafficAnnotationTagTest.java

@@ -0,0 +1,32 @@
+// Copyright 2021 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.net;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.chromium.base.test.BaseRobolectricTestRunner;
+
+/**
+ * Tests calculating the hash for Network Traffic Annotations.
+ */
+@RunWith(BaseRobolectricTestRunner.class)
+public class NetworkTrafficAnnotationTagTest {
+    @Test
+    public void testIterativeHash() throws Exception {
+        // Reference values obtained from
+        // tools/traffic_annotation/scripts/auditor/auditor_tests.py.
+        assertEquals(3556498, NetworkTrafficAnnotationTag.iterativeHash("test"));
+        assertEquals(10236504, NetworkTrafficAnnotationTag.iterativeHash("unique_id"));
+        assertEquals(70581310, NetworkTrafficAnnotationTag.iterativeHash("123_id"));
+        assertEquals(69491511, NetworkTrafficAnnotationTag.iterativeHash("ID123"));
+        assertEquals(98652091,
+                NetworkTrafficAnnotationTag.iterativeHash("a_unique_"
+                        + "looooooooooooooooooooooooooooooooooooooooooooooooooooooong_id"));
+        assertEquals(124751853, NetworkTrafficAnnotationTag.iterativeHash("bébé"));
+    }
+}

net/traffic_annotation/BUILD.gn

@@ -4,6 +4,9 @@ source_set("traffic_annotation") {
     "//base",
     "//build:chromeos_buildflags",
   ]
+  if (is_android) {
+    sources += [ "network_traffic_annotation_android.cc" ]
+  }
 }
 
 source_set("test_support") {

net/traffic_annotation/network_traffic_annotation.h

@@ -12,6 +12,10 @@
 #include "build/build_config.h"
 #include "build/chromeos_buildflags.h"
 
+#if defined(OS_ANDROID)
+#include "base/android/scoped_java_ref.h"
+#endif
+
 namespace {
 
 // Recursively compute hash code of the given string as a constant expression.
@@ -73,6 +77,13 @@ struct NetworkTrafficAnnotationTag {
       const PartialNetworkTrafficAnnotationTag& partial_annotation,
       const char (&proto)[N3]);
 
+#if defined(OS_ANDROID)
+  // Allows C++ methods to receive a Java NetworkTrafficAnnotationTag via JNI,
+  // and convert it to the C++ version.
+  static NetworkTrafficAnnotationTag FromJavaAnnotation(
+      int32_t unique_id_hash_code);
+#endif
+
   friend struct MutableNetworkTrafficAnnotationTag;
 
  private:

net/traffic_annotation/network_traffic_annotation_android.cc

@@ -0,0 +1,15 @@
+// Copyright 2021 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/traffic_annotation/network_traffic_annotation.h"
+
+namespace net {
+
+// static
+NetworkTrafficAnnotationTag NetworkTrafficAnnotationTag::FromJavaAnnotation(
+    int32_t unique_id_hash_code) {
+  return NetworkTrafficAnnotationTag(unique_id_hash_code);
+}
+
+}  // namespace net

tools/traffic_annotation/auditor/safe_list.txt

@@ -9,6 +9,7 @@ missing,net/url_request/url_fetcher.cc
 missing,net/url_request/url_request_context.cc
 mutable_tag,components/download/internal/background_service/proto_conversions.cc
 mutable_tag,chrome/browser/media/router/providers/openscreen/platform/udp_socket.cc
+mutable_tag,net/traffic_annotation/network_traffic_annotation.h
 test_annotation,components/safe_search_api/stub_url_checker.cc
 test_annotation,net/quic/quic_chromium_client_session_peer.cc
 test_annotation,net/tools/quic/quic_http_proxy_backend_stream.cc