WebLayer MediaRouter: remove feature flag in favor of manifest entry.

Instead of using a command line flag, the feature is toggled by an
AndroidManifest entry. This is more ergonomic for developers as they
don't need to use a debug build of Android to toggle the feature.

Bug: 1057100
Change-Id: Icdc6676d1b15e43a46ebb6d14276cef89ff4942f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2480705
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818779}

weblayer/browser/browser_main_parts_impl.cc

@@ -87,7 +87,7 @@ void EnsureBrowserContextKeyedServiceFactoriesBuilt() {
   PrerenderLinkManagerFactory::GetInstance();
   PrerenderManagerFactory::GetInstance();
 #if defined(OS_ANDROID)
-  if (base::FeatureList::IsEnabled(features::kMediaRouter)) {
+  if (MediaRouterFactory::IsFeatureEnabled()) {
     LocalPresentationManagerFactory::GetInstance();
     MediaRouterFactory::GetInstance();
   }

weblayer/browser/content_browser_client_impl.cc

@@ -641,7 +641,7 @@ ContentBrowserClientImpl::GetControllerPresentationServiceDelegate(
   if (WebLayerFactoryImplAndroid::GetClientMajorVersion() < 88)
     return nullptr;
 
-  if (base::FeatureList::IsEnabled(features::kMediaRouter)) {
+  if (MediaRouterFactory::IsFeatureEnabled()) {
     MediaRouterFactory::DoPlatformInitIfNeeded();
     return media_router::PresentationServiceDelegateImpl::
         GetOrCreateForWebContents(web_contents);

weblayer/browser/java/org/chromium/weblayer_private/interfaces/RemoteMediaServiceConstants.java

@@ -6,5 +6,11 @@ package org.chromium.weblayer_private.interfaces;
 
 /** Keys for remote media service intent extras. */
 public interface RemoteMediaServiceConstants {
-    String NOTIFICATION_ID_KEY = "remote_media_service_notification_id_key";
+    // Used as a key in the client's AndroidManifest.xml to enable remote media playback, i.e.
+    // Presentation API, Remote Playback API, and Media Fling (automatic casting of html5 videos).
+    String FEATURE_ENABLED_KEY = "org.chromium.weblayer.ENABLE_REMOTE_MEDIA";
+
+    // Used internally by WebLayer as a key to the various values of remote media service
+    // notification IDs.
+    String NOTIFICATION_ID_KEY = "REMOTE_MEDIA_SERVICE_NOTIFICATION_ID_KEY";
 }

weblayer/browser/java/org/chromium/weblayer_private/media/MediaRouterClientImpl.java

@@ -5,11 +5,16 @@
 package org.chromium.weblayer_private.media;
 
 import android.app.Service;
+import android.content.Context;
 import android.content.Intent;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
 import android.support.v4.media.session.MediaSessionCompat;
 
 import androidx.fragment.app.FragmentManager;
 
+import org.chromium.base.ContextUtils;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.components.browser_ui.media.MediaNotificationController;
@@ -87,6 +92,18 @@ public class MediaRouterClientImpl extends MediaRouterClient {
         MediaRouterClient.setInstance(new MediaRouterClientImpl());
     }
 
+    @CalledByNative
+    public static boolean isMediaRouterEnabled() {
+        Context context = ContextUtils.getApplicationContext();
+        try {
+            ApplicationInfo ai = context.getPackageManager().getApplicationInfo(
+                    context.getPackageName(), PackageManager.GET_META_DATA);
+            return ai.metaData.getBoolean(RemoteMediaServiceConstants.FEATURE_ENABLED_KEY);
+        } catch (NameNotFoundException e) {
+            return false;
+        }
+    }
+
     private static class MediaRouterNotificationControllerDelegate
             implements MediaNotificationController.Delegate {
         // The ID distinguishes between Presentation and Remoting services/notifications.

weblayer/browser/media/media_router_factory.cc

@@ -20,6 +20,13 @@ MediaRouterFactory* MediaRouterFactory::GetInstance() {
   return instance.get();
 }
 
+// static
+bool MediaRouterFactory::IsFeatureEnabled() {
+  static bool enabled = Java_MediaRouterClientImpl_isMediaRouterEnabled(
+      base::android::AttachCurrentThread());
+  return enabled;
+}
+
 // static
 void MediaRouterFactory::DoPlatformInitIfNeeded() {
   static bool init_done = false;

weblayer/browser/media/media_router_factory.h

@@ -25,6 +25,9 @@ class MediaRouterFactory : public media_router::MediaRouterFactory {
 
   static MediaRouterFactory* GetInstance();
 
+  // Determines if media router related features should be enabled.
+  static bool IsFeatureEnabled();
+
   // Performs platform and WebLayer-specific initialization for media_router.
   static void DoPlatformInitIfNeeded();
 

weblayer/common/features.cc

@@ -9,11 +9,6 @@ namespace features {
 
 // Weblayer features in alphabetical order.
 
-// Covers all media router features, i.e. Presentation API, Remote Playback API,
-// and Media Fling (automatic casting of html5 videos).
-const base::Feature kMediaRouter{"WebLayerMediaRouter",
-                                 base::FEATURE_DISABLED_BY_DEFAULT};
-
 // Safebrowsing support for weblayer.
 const base::Feature kWebLayerSafeBrowsing{"WebLayerSafeBrowsing",
                                           base::FEATURE_ENABLED_BY_DEFAULT};

weblayer/common/features.h

@@ -12,8 +12,6 @@ namespace features {
 
 // Weblayer features in alphabetical order.
 
-extern const base::Feature kMediaRouter;
-
 extern const base::Feature kWebLayerSafeBrowsing;
 
 }  // namespace features

weblayer/public/java/org/chromium/weblayer/RemoteMediaService.java

@@ -17,7 +17,18 @@ import org.chromium.weblayer_private.interfaces.RemoteMediaServiceConstants;
  *
  * Like {@link MediaSessionService}, this class is associated with a notification for an ongoing
  * media session. The difference is that the media for this service is played back on a remote
- * device, i.e. casting.
+ * device, i.e. casting. This class can be considered an implementation detail of WebLayer.
+ *
+ * In order to set the Cast application (optional but recommended), the client should add the
+ * following to its manifest:
+ *
+ *    <meta-data
+ *        android:name="org.chromium.content.browser.REMOTE_PLAYBACK_APP_ID"
+ *        android:value="$APP_ID"/>
+ *
+ * Where $APP_ID is the value assigned to your app by the Google Cast SDK Developer Console. If
+ * the cast application ID is not set, the app will appear as "Default Media Receiver" in the
+ * notification, device selection dialog, etc.
  *
  * @since 88
  */

weblayer/shell/android/shell_apk/AndroidManifest.xml

@@ -54,6 +54,8 @@
       </activity>
 
       <!-- Cast support -->
+      <meta-data
+          android:name="org.chromium.weblayer.ENABLE_REMOTE_MEDIA" android:value="true"/>
       <meta-data
           android:name=
           "com.google.android.gms.cast.framework.OPTIONS_PROVIDER_CLASS_NAME"