Add overscroll edge effect animations for 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 3e8c6e019cb49ddf80d38e829629cb3848c77277..7bbf3ed3450b5110ee67e40cd175e2819ab6bf6b 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
@@ -229,6 +229,8 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
 
             @Override
             public void onVSync(long frameTimeMicros) {
+                animateIfNecessary(frameTimeMicros);
+
                 if (mDidSignalVSyncUsingInputEvent) {
                     TraceEvent.instant("ContentViewCore::onVSync ignored");
                     mDidSignalVSyncUsingInputEvent = false;
@@ -273,12 +275,21 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
         while (isVSyncNotificationEnabled()) setVSyncNotificationEnabled(false);
         mVSyncSubscriberCount = 0;
         mVSyncListenerRegistered = false;
+        mNeedAnimate = false;
     }
 
     private boolean isVSyncNotificationEnabled() {
         return mVSyncProvider != null && mVSyncListenerRegistered;
     }
 
+    @CalledByNative
+    private void setNeedsAnimate() {
+        if (!mNeedAnimate) {
+            mNeedAnimate = true;
+            setVSyncNotificationEnabled(true);
+        }
+    }
+
     private final Context mContext;
     private ViewGroup mContainerView;
     private InternalAccessDelegate mContainerViewInternals;
@@ -358,6 +369,9 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
     // Whether we received a new frame since consumePendingRendererFrame() was last called.
     private boolean mPendingRendererFrame = false;
 
+    // Whether we should animate at the next vsync tick.
+    private boolean mNeedAnimate = false;
+
     private ViewAndroid mViewAndroid;
 
     /**
@@ -2774,6 +2788,18 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
         }
     }
 
+    private boolean onAnimate(long frameTimeMicros) {
+        if (mNativeContentViewCore == 0) return false;
+        return nativeOnAnimate(mNativeContentViewCore, frameTimeMicros);
+    }
+
+    private void animateIfNecessary(long frameTimeMicros) {
+        if (mNeedAnimate) {
+            mNeedAnimate = onAnimate(frameTimeMicros);
+            if (!mNeedAnimate) setVSyncNotificationEnabled(false);
+        }
+    }
+
     @CalledByNative
     private void notifyExternalSurface(
             int playerId, boolean isRequest, float x, float y, float width, float height) {
@@ -2944,6 +2970,8 @@ public class ContentViewCore implements MotionEventDelegate, NavigationClient {
 
     private native void nativeOnVSync(int nativeContentViewCoreImpl, long frameTimeMicros);
 
+    private native boolean nativeOnAnimate(int nativeContentViewCoreImpl, long frameTimeMicros);
+
     private native boolean nativePopulateBitmapFromCompositor(int nativeContentViewCoreImpl,
             Bitmap bitmap);