[WebLayer] Move ChromeFeatureList.GENERIC_SENSOR_EXTRA_CLASSES to //services/device

This CL moves the Java-side definition of the kGenericSensorExtraClasses
Feature from ChromeFeatureList to a new DeviceFeatureList class that
lives in //services/device/public/java. This will allow non-Chrome
embedders to query the status of the Feature from Java.

Bug: 1058597
Change-Id: Iab3c75fea6c8755de52714be7776547a774842d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095445
Commit-Queue: Robbie McElrath <rmcelrath@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#750245}

chrome/android/BUILD.gn

@@ -353,6 +353,7 @@ android_library("chrome_java") {
     "//net/android:net_java",
     "//printing:printing_java",
     "//services/data_decoder/public/cpp/android:safe_json_java",
+    "//services/device/public/java:device_feature_list_java",
     "//services/media_session/public/cpp/android:media_session_java",
     "//services/media_session/public/mojom:mojom_java",
     "//services/network/public/mojom:mojom_java",

chrome/android/DEPS

@@ -28,5 +28,6 @@ include_rules = [
   "+components/viz/common/java",
   "+jni",
   "+media/base/android/java",
+  "+services/device/public",
   "+services/media_session/public",
 ]

chrome/android/java/src/org/chromium/chrome/browser/site_settings/ContentSettingsResources.java

@@ -15,8 +15,8 @@ import androidx.annotation.Nullable;
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.ThreadUtils;
 import org.chromium.chrome.R;
-import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.components.content_settings.ContentSettingsType;
+import org.chromium.device.DeviceFeatureList;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -190,15 +190,15 @@ public class ContentSettingsResources {
             int sensorsBlockedDescription =
                     R.string.website_settings_category_motion_sensors_blocked;
             try {
-                if (ChromeFeatureList.isEnabled(ChromeFeatureList.GENERIC_SENSOR_EXTRA_CLASSES)) {
+                if (DeviceFeatureList.isEnabled(DeviceFeatureList.GENERIC_SENSOR_EXTRA_CLASSES)) {
                     sensorsPermissionTitle = R.string.sensors_permission_title;
                     sensorsAllowedDescription = R.string.website_settings_category_sensors_allowed;
                     sensorsBlockedDescription = R.string.website_settings_category_sensors_blocked;
                 }
             } catch (IllegalArgumentException e) {
                 // We can hit this in tests that use the @Features annotation, as it calls
-                // ChromeFeatureList.setTestFeatures() with a map that should not need to contain
-                // ChromeFeatureList.GENERIC_SENSOR_EXTRA_CLASSES.
+                // FeatureList.setTestFeatures() with a map that should not need to contain
+                // DeviceFeatureList.GENERIC_SENSOR_EXTRA_CLASSES.
             }
             localMap.put(ContentSettingsType.SENSORS,
                     new ResourceItem(R.drawable.settings_sensors, sensorsPermissionTitle,

chrome/browser/BUILD.gn

@@ -3025,6 +3025,7 @@ jumbo_static_library("browser") {
       "//rlz:rlz_utils",
       "//sandbox",
       "//sandbox:sandbox_buildflags",
+      "//services/device/public/cpp:device_feature_list",
       "//services/proxy_resolver:lib",
       "//third_party/android_ndk:cpu_features",
       "//third_party/android_opengl/etc1",

chrome/browser/flags/android/java/src/org/chromium/chrome/browser/flags/ChromeFeatureList.java

@@ -285,7 +285,6 @@ public abstract class ChromeFeatureList {
     public static final String EXPLORE_SITES = "ExploreSites";
     public static final String FOCUS_OMNIBOX_IN_INCOGNITO_TAB_INTENTS =
             "FocusOmniboxInIncognitoTabIntents";
-    public static final String GENERIC_SENSOR_EXTRA_CLASSES = "GenericSensorExtraClasses";
     public static final String GRANT_NOTIFICATIONS_TO_DSE = "GrantNotificationsToDSE";
     public static final String HANDLE_MEDIA_INTENTS = "HandleMediaIntents";
     public static final String HOMEPAGE_LOCATION_POLICY = "HomepageLocationPolicy";

services/device/BUILD.gn

@@ -349,6 +349,7 @@ if (is_android) {
   generate_jni("device_service_jni_headers") {
     sources = [
       "android/java/src/org/chromium/services/device/InterfaceRegistrar.java",
+      "public/java/src/org/chromium/device/DeviceFeatureList.java",
     ]
   }
 

services/device/public/cpp/BUILD.gn

@@ -16,6 +16,17 @@ component("device_features") {
   defines = [ "DEVICE_FEATURES_IMPLEMENTATION" ]
 }
 
+if (is_android) {
+  source_set("device_feature_list") {
+    sources = [ "device_feature_list.cc" ]
+    deps = [
+      ":device_features",
+      "//base",
+      "//services/device:device_service_jni_headers",
+    ]
+  }
+}
+
 source_set("test_support") {
   testonly = true
 

services/device/public/cpp/device_feature_list.cc

@@ -0,0 +1,50 @@
+// Copyright 2020 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 "base/android/jni_string.h"
+#include "base/feature_list.h"
+#include "base/stl_util.h"
+#include "services/device/device_service_jni_headers/DeviceFeatureList_jni.h"
+#include "services/device/public/cpp/device_features.h"
+
+using base::android::ConvertJavaStringToUTF8;
+using base::android::JavaParamRef;
+
+namespace features {
+
+namespace {
+
+// Array of features exposed through the Java ContentFeatureList API. Entries in
+// this array may either refer to features defined in the header of this file or
+// in other locations in the code base (e.g. content_features.h).
+const base::Feature* kFeaturesExposedToJava[] = {
+    &kGenericSensorExtraClasses,
+};
+
+// TODO(crbug.com/1060097): Removethis once a generalized FeatureList exists.
+const base::Feature* FindFeatureExposedToJava(const std::string& feature_name) {
+  for (size_t i = 0; i < base::size(kFeaturesExposedToJava); ++i) {
+    if (kFeaturesExposedToJava[i]->name == feature_name)
+      return kFeaturesExposedToJava[i];
+  }
+  NOTREACHED() << "Queried feature cannot be found in DeviceFeatureList: "
+               << feature_name;
+  return nullptr;
+}
+
+}  // namespace
+
+static jboolean JNI_DeviceFeatureList_IsInitialized(JNIEnv* env) {
+  return !!base::FeatureList::GetInstance();
+}
+
+static jboolean JNI_DeviceFeatureList_IsEnabled(
+    JNIEnv* env,
+    const JavaParamRef<jstring>& jfeature_name) {
+  const base::Feature* feature =
+      FindFeatureExposedToJava(ConvertJavaStringToUTF8(env, jfeature_name));
+  return base::FeatureList::IsEnabled(*feature);
+}
+
+}  // namespace features

services/device/public/java/BUILD.gn

@@ -4,6 +4,15 @@
 
 import("//build/config/android/rules.gni")
 
+android_library("device_feature_list_java") {
+  sources = [ "src/org/chromium/device/DeviceFeatureList.java" ]
+  deps = [
+    "//base:base_java",
+    "//base:jni_java",
+  ]
+  annotation_processor_deps = [ "//base/android/jni_generator:jni_processor" ]
+}
+
 android_library("nfc_java") {
   sources = [ "src/org/chromium/device/nfc/NfcDelegate.java" ]
   deps = [ "//base:base_java" ]

services/device/public/java/src/org/chromium/device/DeviceFeatureList.java

@@ -0,0 +1,63 @@
+// Copyright 2020 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.device;
+
+import org.chromium.base.FeatureList;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.MainDex;
+import org.chromium.base.annotations.NativeMethods;
+import org.chromium.base.library_loader.LibraryLoader;
+
+/**
+ * Provides an API for querying the status of Device Service Features.
+ */
+// TODO(crbug.com/1060097): Remove/update this once a generalized FeatureList exists.
+@JNINamespace("features")
+@MainDex
+public class DeviceFeatureList {
+    public static final String GENERIC_SENSOR_EXTRA_CLASSES = "GenericSensorExtraClasses";
+
+    private DeviceFeatureList() {}
+
+    /**
+     * Returns whether the specified feature is enabled or not.
+     *
+     * Note: Features queried through this API must be added to the array
+     * |kFeaturesExposedToJava| in //services/device/public/cpp/device_features.cc
+     *
+     * @param featureName The name of the feature to query.
+     * @return Whether the feature is enabled or not.
+     */
+    public static boolean isEnabled(String featureName) {
+        Boolean testValue = FeatureList.getTestValueForFeature(featureName);
+        if (testValue != null) return testValue;
+        assert isNativeInitialized();
+        return DeviceFeatureListJni.get().isEnabled(featureName);
+    }
+
+    /**
+     * @return Whether the native FeatureList is initialized or not.
+     */
+    private static boolean isNativeInitialized() {
+        if (FeatureList.hasTestFeatures()) return true;
+
+        if (!LibraryLoader.getInstance().isInitialized()) return false;
+        // Even if the native library is loaded, the C++ FeatureList might not be initialized yet.
+        // In that case, accessing it will not immediately fail, but instead cause a crash later
+        // when it is initialized. Return whether the native FeatureList has been initialized,
+        // so the return value can be tested, or asserted for a more actionable stack trace
+        // on failure.
+        //
+        // The FeatureList is however guaranteed to be initialized by the time
+        // AsyncInitializationActivity#finishNativeInitialization is called.
+        return DeviceFeatureListJni.get().isInitialized();
+    }
+
+    @NativeMethods
+    interface Natives {
+        boolean isInitialized();
+        boolean isEnabled(String featureName);
+    }
+}