[Android] Port OverScrolled Event to ContentViewClient for Crosswalk.

OverScrolled Event could be catch by WebView through Android View
System. But XWalkView is not a true view, so XWalkView need this patch
to port OverScrolled Event to it.

BUG=XWALK-4871
BUG=XWALK-4894

content/browser/android/content_view_core_impl.cc

@@ -694,6 +694,14 @@ bool ContentViewCoreImpl::ShouldBlockMediaRequest(const GURL& url) {
                                                       j_url.obj());
 }
 
+void ContentViewCoreImpl::DidOverscroll(bool clampedX, bool clampedY) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  ScopedJavaLocalRef<jobject> j_obj = java_ref_.get(env);
+  if (!j_obj.is_null()) {
+    Java_ContentViewCore_didOverscroll(env, j_obj.obj(), clampedX, clampedY);
+  }
+}
+
 void ContentViewCoreImpl::DidStopFlinging() {
   JNIEnv* env = AttachCurrentThread();
 

content/browser/android/content_view_core_impl.h

@@ -284,6 +284,8 @@ class ContentViewCoreImpl : public ContentViewCore,
 
   void DidStopFlinging();
 
+  void DidOverscroll(bool clampedX, bool clampedY);
+
   // Returns the context with which the ContentViewCore was created, typically
   // the Activity context.
   base::android::ScopedJavaLocalRef<jobject> GetContext() const;

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -1768,6 +1768,10 @@ void RenderWidgetHostViewAndroid::DidOverscroll(
 
   if (overscroll_controller_)
     overscroll_controller_->OnOverscrolled(params);
+
+  bool clampedX = params.latest_overscroll_delta.x() != 0 ? true : false;
+  bool clampedY = params.latest_overscroll_delta.y() != 0 ? true : false;
+  content_view_core_->DidOverscroll(clampedX, clampedY);
 }
 
 void RenderWidgetHostViewAndroid::DidStopFlinging() {

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

@@ -224,4 +224,10 @@ public int getDesiredWidthMeasureSpec() {
     public int getDesiredHeightMeasureSpec() {
         return UNSPECIFIED_MEASURE_SPEC;
     }
+
+    /**
+     * Called when overscroll event has been fired
+     **/
+    public void onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY) {
+    }
 }

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

@@ -3363,6 +3363,14 @@ public void setContextualSearchClient(ContextualSearchClient contextualSearchCli
         mContextualSearchClient = contextualSearchClient;
     }
 
+    @CalledByNative
+    public void didOverscroll(boolean clampedX, boolean clampedY) {
+        mContentViewClient.onOverScrolled(mRenderCoordinates.getScrollXPixInt(),
+                                          mRenderCoordinates.getScrollYPixInt(),
+                                          clampedX,
+                                          clampedY);
+    }
+
     private native long nativeInit(WebContents webContents, ViewAndroidDelegate viewAndroidDelegate,
             long windowAndroidPtr, HashSet<Object> retainedObjectSet);
     private static native ContentViewCore nativeFromWebContentsAndroid(WebContents webContents);