Reland "WebView: Implement request monitor in EmbeddedTestServerAndroid"

This reverts commit 369c5093d8.

Reason for revert (reland):
The original CL was reverted due to compile failures on the Cronet bot.
This is because the code generated by AIDL used a language feature that
requires SDK version 24 for Map<String, String>, but the Cronet requires
SDK version 23 as the minimum version (https://crrev.com/c/5913439). To
avoid the restriction, this CL encodes the headers into String[] that
should be available even in SDK version 23 instead of Map.

Original change's description:
> Revert "WebView: Implement request monitor in EmbeddedTestServerAndroid"
>
> This reverts commit 3d9eb93fb1.
>
> Reason for revert:
> This CL breaks the android-cronet-arm-dbg build:
> https://ci.chromium.org/b/8729401193435602897
>
> Original change's description:
> > WebView: Implement request monitor in EmbeddedTestServerAndroid
> >
> > This CL implements the request monitor to capture request headers in
> > EmbeddedTestServerAndroid. The headers are exposed to Java, so that
> > WebView tests can check if requests have appropriate headers.
> >
> > As an example usage, this CL uses the mechanism in a prerendering test.
> > The test checks if prerendering navigation has the Sec-Purpose header.
> >
> > Change-Id: Iec9843917fc4ac3cafa15b71304ba92352502635
> > Bug: 41490450
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6072982
> > Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
> > Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
> > Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#1392138}
>
> Bug: 41490450
> Change-Id: Id50f9bc047209bd593a015373b93e7bbceaf3b0c
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6072588
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> Auto-Submit: Hiroki Nakagawa <nhiroki@chromium.org>
> Owners-Override: Yifan Luo <lyf@chromium.org>
> Commit-Queue: Yifan Luo <lyf@chromium.org>
> Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1392197}

Bug: 41490450
Change-Id: Ib189894a9df2e5923564fe81fc95129db0ce2b94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6072608
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1392770}

android_webview/javatests/src/org/chromium/android_webview/test/AwPrerenderTest.java

@@ -402,6 +402,10 @@ public class AwPrerenderTest extends AwParameterizedTest {
         Assert.assertEquals(onPageStartedHelper.getCallCount(), 1);
         Assert.assertEquals(onPageStartedHelper.getUrl(), mPageUrl);
 
+        // Make sure that prerendering navigation has the Sec-Purpose header.
+        HashMap<String, String> headers = mTestServer.getRequestHeadersForUrl(PRERENDER_URL);
+        Assert.assertEquals("prefetch;prerender", headers.get("Sec-Purpose"));
+
         activatePage(mPrerenderingUrl, ActivationBy.LOAD_URL);
 
         // Wait until the navigation activates the prerendered page.

net/test/android/javatests/src/org/chromium/net/test/EmbeddedTestServer.java

@@ -24,11 +24,13 @@ import org.chromium.net.X509Util;
 import org.chromium.net.test.util.CertTestUtil;
 
 import java.io.File;
+import java.util.HashMap;
 
 /**
  * A simple file server for java tests.
  *
  * An example use:
+ *
  * <pre>
  * EmbeddedTestServer s = EmbeddedTestServer.createAndStartServer(context);
  *
@@ -470,12 +472,12 @@ public class EmbeddedTestServer {
         }
     }
 
-    /** Get the full URLs for the given relative URLs.
+    /**
+     * Get the full URLs for the given relative URLs.
      *
-     *  @see #getURL(String)
-     *
-     *  @param relativeUrls The relative URLs for which full URLs will be obtained.
-     *  @return The URLs as a String array.
+     * @see #getURL(String)
+     * @param relativeUrls The relative URLs for which full URLs will be obtained.
+     * @return The URLs as a String array.
      */
     public String[] getURLs(String... relativeUrls) {
         String[] absoluteUrls = new String[relativeUrls.length];
@@ -485,10 +487,37 @@ public class EmbeddedTestServer {
         return absoluteUrls;
     }
 
+    /**
+     * Get the request headers observed on the server for the given relative URL.
+     *
+     * @param relativeUrl The relative URL for which request headers should be returned.
+     * @return The map of the header key and value pairs.
+     */
+    public HashMap<String, String> getRequestHeadersForUrl(final String relativeUrl) {
+        try {
+            synchronized (mImplMonitor) {
+                checkServiceLocked();
+                String[] headers_array = mImpl.getRequestHeadersForUrl(relativeUrl);
+                // The length of the vector should be even, as the vector alternates between header
+                // names (even indices) and their corresponding values (odd indices).
+                Assert.assertEquals(0, headers_array.length % 2);
+
+                HashMap<String, String> headers = new HashMap<String, String>();
+                for (int i = 0; i < headers_array.length; i += 2) {
+                    headers.put(headers_array[i], headers_array[i + 1]);
+                }
+                return headers;
+            }
+        } catch (RemoteException e) {
+            throw new EmbeddedTestServerFailure(
+                    "Failed to get request headers for " + relativeUrl, e);
+        }
+    }
+
     /**
      * Stop and destroy the server.
      *
-     *  This handles stopping the server and destroying the native object.
+     * This handles stopping the server and destroying the native object.
      */
     public void stopAndDestroyServer() {
         synchronized (mImplMonitor) {

net/test/android/javatests/src/org/chromium/net/test/EmbeddedTestServerImpl.java

@@ -12,6 +12,7 @@ import android.os.RemoteException;
 
 import org.jni_zero.CalledByNative;
 import org.jni_zero.JNINamespace;
+import org.jni_zero.JniType;
 import org.jni_zero.NativeMethods;
 
 import org.chromium.base.ContextUtils;
@@ -257,9 +258,29 @@ public class EmbeddedTestServerImpl extends IEmbeddedTestServerImpl.Stub {
                 });
     }
 
-    /** Shut down the server.
+    /**
+     * Get the request headers observed on the server for the given relative URL.
      *
-     *  @return Whether the server was successfully shut down.
+     * @param relativeUrl The relative URL for which request headers should be returned.
+     * @return The vector alternates between header names (even indices) and their corresponding
+     *     values (odd indices).
+     */
+    @Override
+    public String[] getRequestHeadersForUrl(final String relativeUrl) {
+        return runOnHandlerThread(
+                new Callable<String[]>() {
+                    @Override
+                    public String[] call() {
+                        return EmbeddedTestServerImplJni.get()
+                                .getRequestHeadersForUrl(mNativeEmbeddedTestServer, relativeUrl);
+                    }
+                });
+    }
+
+    /**
+     * Shut down the server.
+     *
+     * @return Whether the server was successfully shut down.
      */
     @Override
     public boolean shutdownAndWaitUntilComplete() {
@@ -362,5 +383,8 @@ public class EmbeddedTestServerImpl extends IEmbeddedTestServerImpl.Stub {
                 long nativeEmbeddedTestServerAndroid, String hostName, String relativeUrl);
 
         void serveFilesFromDirectory(long nativeEmbeddedTestServerAndroid, String directoryPath);
+
+        @JniType("std::vector<std::string>")
+        String[] getRequestHeadersForUrl(long nativeEmbeddedTestServerAndroid, String relativeUrl);
     }
 }

net/test/android/javatests/src/org/chromium/net/test/IEmbeddedTestServerImpl.aidl

@@ -60,6 +60,21 @@ interface IEmbeddedTestServerImpl {
      */
     String getURLWithHostName(String hostName, String relativeUrl);
 
+    /** Get the request headers observed on the server for the given relative URL.
+     *
+     *  @param relativeUrl The relative URL for which request headers should be returned.
+     *  @return The vector alternates between header names (even indices) and their corresponding
+     *      values (odd indices).
+     *
+     *  Ideally the returned type should be map but it is not available due to the required SDK
+     *  version in Cronet. The generated code for the map requires SDK 24, but
+     *  the Cronet requires SDK 23 as the minimum version (https://crrev.com/c/5913439).
+     *
+     *  Note that the HTTP spec allows to have multiple headers for the same name, but the returned
+     *  vector only contains one of them. See https://crbug.com/382316472 for details.
+     */
+    String[] getRequestHeadersForUrl(String relativeUrl);
+
     /** Shut down the server.
      *
      *  @return Whether the server was successfully shut down.

net/test/embedded_test_server/android/embedded_test_server_android.cc

@@ -54,6 +54,11 @@ EmbeddedTestServerAndroid::EmbeddedTestServerAndroid(
   test_server_.SetConnectionListener(&connection_listener_);
   Java_EmbeddedTestServerImpl_setNativePtr(env, jobj,
                                            reinterpret_cast<intptr_t>(this));
+
+  // Register the request monitor to capture request headers.
+  test_server_.RegisterRequestMonitor(
+      base::BindRepeating(&EmbeddedTestServerAndroid::MonitorResourceRequest,
+                          base::Unretained(this)));
 }
 
 EmbeddedTestServerAndroid::~EmbeddedTestServerAndroid() {
@@ -93,6 +98,26 @@ ScopedJavaLocalRef<jstring> EmbeddedTestServerAndroid::GetURLWithHostName(
   return base::android::ConvertUTF8ToJavaString(env, gurl.spec());
 }
 
+std::vector<std::string> EmbeddedTestServerAndroid::GetRequestHeadersForUrl(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jstring>& jrelative_url) {
+  base::AutoLock auto_lock(lock_);
+  std::string path = base::android::ConvertJavaStringToUTF8(env, jrelative_url);
+  CHECK(request_headers_by_path_.contains(path)) << path;
+
+  // Copy headers from HttpRequest::HeaderMap to std::vector for passing them to
+  // Java. For the required SDK version in Cronet, std::map is not available
+  // (see the comment in IEmbeddedTestServerImpl.aidl for details). The vector
+  // alternates between header names (even indices) and their corresponding
+  // values (odd indices).
+  std::vector<std::string> headers;
+  for (auto [key, value] : request_headers_by_path_[path]) {
+    headers.push_back(key);
+    headers.push_back(value);
+  }
+  return headers;
+}
+
 void EmbeddedTestServerAndroid::AddDefaultHandlers(
     JNIEnv* env,
     const JavaParamRef<jstring>& jdirectory_path) {
@@ -156,4 +181,11 @@ static void JNI_EmbeddedTestServerImpl_Init(
   new EmbeddedTestServerAndroid(env, jobj, jhttps);
 }
 
+void EmbeddedTestServerAndroid::MonitorResourceRequest(
+    const net::test_server::HttpRequest& request) {
+  base::AutoLock auto_lock(lock_);
+  request_headers_by_path_.emplace(request.GetURL().PathForRequest(),
+                                   request.headers);
+}
+
 }  // namespace net::test_server

net/test/embedded_test_server/android/embedded_test_server_android.h

@@ -10,6 +10,7 @@
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/memory/raw_ptr.h"
+#include "base/synchronization/lock.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
 #include "net/test/embedded_test_server/embedded_test_server_connection_listener.h"
 #include "net/test/embedded_test_server/http_request.h"
@@ -48,6 +49,10 @@ class EmbeddedTestServerAndroid {
       const base::android::JavaParamRef<jstring>& jhostname,
       const base::android::JavaParamRef<jstring>& jrelative_url) const;
 
+  std::vector<std::string> GetRequestHeadersForUrl(
+      JNIEnv* env,
+      const base::android::JavaParamRef<jstring>& jrelative_url);
+
   void AddDefaultHandlers(
       JNIEnv* jenv,
       const base::android::JavaParamRef<jstring>& jdirectory_path);
@@ -81,10 +86,21 @@ class EmbeddedTestServerAndroid {
   void AcceptedSocket(const void* socket_id);
   void ReadFromSocket(const void* socket_id);
 
+  void MonitorResourceRequest(const net::test_server::HttpRequest& request);
+
   JavaObjectWeakGlobalRef weak_java_server_;
 
   EmbeddedTestServer test_server_;
   ConnectionListener connection_listener_;
+
+  // Headers of requests sent to the server. Keyed by path (not by full URL)
+  // because the host part of the requests is translated ("a.test" to
+  // "127.0.0.1") before the server handles them.
+  // This is accessed from the UI thread and `EmbeddedTestServer::io_thread_`,
+  // so it's guarded by the lock.
+  std::map<std::string, net::test_server::HttpRequest::HeaderMap>
+      request_headers_by_path_ GUARDED_BY(lock_);
+  base::Lock lock_;
 };
 
 }  // namespace net::test_server