Implement vsync notification on Android

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 9d157ae697f967b87f21c444b38c2c87db0d3619..e47c5af636c58fc87ab3f8906c98587569034afb 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -167,6 +167,35 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
         void onContentSizeChanged(int contentWidthPix, int contentHeightPix);
     }
 
+    /**
+     * Interface for requesting notification of the display vsync signal.
+     * The provider will call ContentViewCore.sendVSync() to notify about vsync.
+     */
+    public static interface VSyncProvider {
+        void setVSyncNotificationEnabled(ContentViewCore contentViewCore, boolean enable);
+    }
+
+    private VSyncProvider mVSyncProvider;
+    private int mVSyncSubscriberCount;
+
+    public void setVSyncProvider(VSyncProvider vsyncProvider) {
+        mVSyncProvider = vsyncProvider;
+    }
+
+    @CalledByNative
+    void setVSyncNotificationEnabled(boolean enabled) {
+        mVSyncSubscriberCount += enabled ? 1 : -1;
+        assert mVSyncSubscriberCount >= 0;
+        if (mVSyncProvider != null) {
+            mVSyncProvider.setVSyncNotificationEnabled(this, mVSyncSubscriberCount > 0);
+        }
+    }
+
+    @CalledByNative
+    private void resetVSyncNotification() {
+        while (mVSyncSubscriberCount > 0) setVSyncNotificationEnabled(false);
+    }
+
     private final Context mContext;
     private ViewGroup mContainerView;
     private InternalAccessDelegate mContainerViewInternals;
@@ -633,6 +662,7 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
         if (mNativeContentViewCore != 0) {
             nativeOnJavaContentViewCoreDestroyed(mNativeContentViewCore);
         }
+        resetVSyncNotification();
         mNativeContentViewCore = 0;
         mContentSettings = null;
         mJavaScriptInterfaces.clear();
@@ -2614,6 +2644,16 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
     }
 
     /**
+     * Send a vsync signal to the renderer.
+     * @param frameTimeMicros The latest vsync frame time in microseconds.
+     */
+    public void sendVSync(long frameTimeMicros) {
+        if (mNativeContentViewCore != 0) {
+            nativeSendVSync(mNativeContentViewCore, frameTimeMicros);
+        }
+    }
+
+    /**
      * @return The cached copy of render positions and scales.
      */
     public RenderCoordinates getRenderCoordinates() {
@@ -2793,6 +2833,8 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
     private native void nativeUpdateVSyncParameters(int nativeContentViewCoreImpl,
             long timebaseMicros, long intervalMicros);
 
+    private native void nativeSendVSync(int nativeContentViewCoreImpl, long frameTimeMicros);
+
     private native boolean nativePopulateBitmapFromCompositor(int nativeContentViewCoreImpl,
             Bitmap bitmap);