Make it possible for the scroll offset delegate to intercept fling.

android_webview/java/src/org/chromium/android_webview/AwContents.java

Index: android_webview/java/src/org/chromium/android_webview/AwContents.java
diff --git a/android_webview/java/src/org/chromium/android_webview/AwContents.java b/android_webview/java/src/org/chromium/android_webview/AwContents.java
index bd6433696783deb62c4fb9accb934faa7c257487..3ed9aec26d94ee3496b38e63060aec3033d282c7 100644
--- a/android_webview/java/src/org/chromium/android_webview/AwContents.java
+++ b/android_webview/java/src/org/chromium/android_webview/AwContents.java
@@ -31,6 +31,7 @@ import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
 import android.webkit.GeolocationPermissions;
 import android.webkit.ValueCallback;
+import android.widget.OverScroller;
 
 import com.google.common.annotations.VisibleForTesting;
 
@@ -374,10 +375,15 @@ public class AwContents {
         public int getContainerViewScrollY() {
             return mContainerView.getScrollY();
         }
+
+        @Override
+        public void invalidate() {
+            mContainerView.invalidate();
+        }
     }
 
     //--------------------------------------------------------------------------------------------
-    private class AwPinchGestureStateListener implements ContentViewCore.PinchGestureStateListener {
+    private class AwGestureStateListener implements ContentViewCore.GestureStateListener {
         @Override
         public void onPinchGestureStart() {
             // While it's possible to re-layout the view during a pinch gesture, the effect is very
@@ -389,9 +395,20 @@ public class AwContents {
             mLayoutSizer.freezeLayoutRequests();
         }
 
+        @Override
         public void onPinchGestureEnd() {
             mLayoutSizer.unfreezeLayoutRequests();
         }
+
+        @Override
+        public void onFlingStartGestureStart(int vx, int vy) {
+            mScrollOffsetManager.onFlingStartGestureStart(vx, vy);
+        }
+
+        @Override
+        public void onUnhandledFlingStartEvent() {
+            mScrollOffsetManager.onUnhandledFlingStartEvent();
+        }
     }
 
     //--------------------------------------------------------------------------------------------
@@ -426,7 +443,7 @@ public class AwContents {
 
     private static ContentViewCore createAndInitializeContentViewCore(ViewGroup containerView,
             InternalAccessDelegate internalDispatcher, int nativeWebContents,
-            ContentViewCore.PinchGestureStateListener pinchGestureStateListener,
+            ContentViewCore.GestureStateListener pinchGestureStateListener,
             ContentViewClient contentViewClient,
             ContentViewCore.ZoomControlsDelegate zoomControlsDelegate) {
       ContentViewCore contentViewCore = new ContentViewCore(containerView.getContext());
@@ -434,7 +451,7 @@ public class AwContents {
       // compositor, not because input events are delivered immediately.
       contentViewCore.initialize(containerView, internalDispatcher, nativeWebContents, null,
                 ContentViewCore.INPUT_EVENTS_DELIVERED_IMMEDIATELY);
-      contentViewCore.setPinchGestureStateListener(pinchGestureStateListener);
+      contentViewCore.setGestureStateListener(pinchGestureStateListener);
       contentViewCore.setContentViewClient(contentViewClient);
       contentViewCore.setZoomControlsDelegate(zoomControlsDelegate);
       return contentViewCore;
@@ -481,7 +498,8 @@ public class AwContents {
         mSettings.setDefaultVideoPosterURL(
                 mDefaultVideoPosterRequestHandler.getDefaultVideoPosterURL());
         mContentsClient.setDIPScale(mDIPScale);
-        mScrollOffsetManager = new AwScrollOffsetManager(new AwScrollOffsetManagerDelegate());
+        mScrollOffsetManager = new AwScrollOffsetManager(new AwScrollOffsetManagerDelegate(),
+                new OverScroller(mContainerView.getContext()));
 
         setOverScrollMode(mContainerView.getOverScrollMode());
 
@@ -515,7 +533,7 @@ public class AwContents {
         int nativeWebContents = nativeGetWebContents(mNativeAwContents);
         mContentViewCore = createAndInitializeContentViewCore(
                 mContainerView, mInternalAccessAdapter, nativeWebContents,
-                new AwPinchGestureStateListener(), mContentsClient.getContentViewClient(),
+                new AwGestureStateListener(), mContentsClient.getContentViewClient(),
                 mZoomControls);
         nativeSetJavaPeers(mNativeAwContents, this, mWebContentsDelegate, mContentsClientBridge,
                 mIoThreadClient, mInterceptNavigationDelegate);
@@ -874,6 +892,13 @@ public class AwContents {
     }
 
     /**
+     * @see View.computeScroll()
+     */
+    public void computeScroll() {
+        mScrollOffsetManager.computeScrollAndAbsorbGlow(mOverScrollGlow);
+    }
+
+    /**
      * @see View#computeHorizontalScrollRange()
      */
     public int computeHorizontalScrollRange() {
@@ -1277,6 +1302,10 @@ public class AwContents {
             mOverScrollGlow.releaseAll();
         }
 
+        if (event.getActionMasked() == MotionEvent.ACTION_DOWN) {
+            mScrollOffsetManager.onTouchDown();
+        }
+
         return rv;
     }
 
@@ -1662,7 +1691,7 @@ public class AwContents {
             mOverScrollGlow.setOverScrollDeltas(deltaX, deltaY);
         }
 
-        mScrollOffsetManager.overscrollBy(deltaX, deltaY);
+        mScrollOffsetManager.overScrollBy(deltaX, deltaY);
 
         if (mOverScrollGlow != null && mOverScrollGlow.isAnimating()) {
             mContainerView.invalidate();