Let the browser know the end of fling

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 30a5d3eac45087bc0adba8df73c82720af7da65d..b5f22bc55b70c1ee0b72dc6716b0c341735d8b97 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
@@ -1363,6 +1363,7 @@ public class ContentViewCore
         if (mGestureStateListener != null) {
             mGestureStateListener.onUnhandledFlingStartEvent();
         }
+        mContentViewClient.onFlingStopped();
     }
 
     @SuppressWarnings("unused")
@@ -1428,6 +1429,12 @@ public class ContentViewCore
                 nativeScrollEnd(mNativeContentViewCore, timeMs);
                 return true;
             case ContentViewGestureHandler.GESTURE_FLING_START:
+                // As onNativeFlingStarted() may be delayed, here let the client know the
+                // possible fling earlier. If the fling is not handled by native side
+                // (i.e. no onNativeFlingStarted() or onNativeFlingStopped() will be called),
+                // onFlingStopped() will be called from unhandledFlingStartEvent().

[jdduke (slow), 2014/01/10 17:45:59]

So we may get a redundant |onFlingStarted()| call from native? I guess that's OK
as long as there's always a terminal |onFlingStopped()|.

[Xianzhu, 2014/01/10 20:16:02]

Yes, the redundancy is to handle the gap. Added comments about it.

+                mContentViewClient.onFlingStarted();
+
                 nativeFlingStart(mNativeContentViewCore, timeMs, x, y,
                         b.getInt(ContentViewGestureHandler.VELOCITY_X, 0),
                         b.getInt(ContentViewGestureHandler.VELOCITY_Y, 0));
@@ -3257,6 +3264,16 @@ public class ContentViewCore
         return getContentViewClient().shouldBlockMediaRequest(url);
     }
 
+    @CalledByNative
+    private void onNativeFlingStarted() {
+        getContentViewClient().onFlingStarted();
+    }
+
+    @CalledByNative
+    private void onNativeFlingStopped() {
+        getContentViewClient().onFlingStopped();
+    }
+
     private native WebContents nativeGetWebContentsAndroid(long nativeContentViewCoreImpl);
 
     private native void nativeOnJavaContentViewCoreDestroyed(long nativeContentViewCoreImpl);