[Android] Prevent touch interception for browser-consumed touches

Browser-based widgets that overlay content have a shot at consuming
touch events, e.g., selection handles. Such touches are reported as
consumed to the View chain, however, embedding apps still have the
opportunity to intercept those touch sequences. This can lead to
double-handling, e.g., when dragging a selection handle left or
right and triggering a View side swipe.

Prevent this by calling requestDisallowInterceptTouchEvent() for
touches that are consumed by such browser-based widgets. Note that we
cannot call this method for all touch events as touch dispatch is often
asynchronous and the disposition of the touch handling result cannot
be immediately known when the touch is received from the Android
platform.

BUG=489337

Review URL: https://codereview.chromium.org/1140693004

Cr-Commit-Position: refs/heads/master@{#330426}

content/browser/android/content_view_core_impl.cc

@@ -583,6 +583,13 @@ bool ContentViewCoreImpl::HasFocus() {
   return Java_ContentViewCore_hasFocus(env, obj.obj());
 }
 
+void ContentViewCoreImpl::RequestDisallowInterceptTouchEvent() {
+  JNIEnv* env = AttachCurrentThread();
+  ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
+  if (!obj.is_null())
+    Java_ContentViewCore_requestDisallowInterceptTouchEvent(env, obj.obj());
+}
+
 void ContentViewCoreImpl::OnSelectionChanged(const std::string& text) {
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);

content/browser/android/content_view_core_impl.h

@@ -239,6 +239,7 @@ class ContentViewCoreImpl : public ContentViewCore,
   void OnBackgroundColorChanged(SkColor color);
 
   bool HasFocus();
+  void RequestDisallowInterceptTouchEvent();
   void OnGestureEventAck(const blink::WebGestureEvent& event,
                          InputEventAckState ack_result);
   bool FilterInputEvent(const blink::WebInputEvent& event);

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -748,12 +748,19 @@ bool RenderWidgetHostViewAndroid::OnTouchEvent(
   if (!host_)
     return false;
 
+  // If a browser-based widget consumes the touch event, it's critical that
+  // touch event interception be disabled. This avoids issues with
+  // double-handling for embedder-detected gestures like side swipe.
   if (selection_controller_ &&
-      selection_controller_->WillHandleTouchEvent(event))
+      selection_controller_->WillHandleTouchEvent(event)) {
+    RequestDisallowInterceptTouchEvent();
     return true;
+  }
 
-  if (stylus_text_selector_.OnTouchEvent(event))
+  if (stylus_text_selector_.OnTouchEvent(event)) {
+    RequestDisallowInterceptTouchEvent();
     return true;
+  }
 
   ui::FilteredGestureProvider::TouchHandlingResult result =
       gesture_provider_.OnTouchEvent(event);
@@ -782,13 +789,20 @@ bool RenderWidgetHostViewAndroid::OnTouchHandleEvent(
 void RenderWidgetHostViewAndroid::ResetGestureDetection() {
   const ui::MotionEvent* current_down_event =
       gesture_provider_.GetCurrentDownEvent();
-  if (current_down_event) {
-    scoped_ptr<ui::MotionEvent> cancel_event = current_down_event->Cancel();
-    OnTouchEvent(*cancel_event);
+  if (!current_down_event) {
+    // A hard reset ensures prevention of any timer-based events that might fire
+    // after a touch sequence has ended.
+    gesture_provider_.ResetDetection();
+    return;
   }
 
-  // A hard reset ensures prevention of any timer-based events.
-  gesture_provider_.ResetDetection();
+  scoped_ptr<ui::MotionEvent> cancel_event = current_down_event->Cancel();
+  if (gesture_provider_.OnTouchEvent(*cancel_event).succeeded) {
+    bool causes_scrolling = false;
+    host_->ForwardTouchEventWithLatencyInfo(
+        ui::CreateWebTouchEventFromMotionEvent(*cancel_event, causes_scrolling),
+        ui::LatencyInfo());
+  }
 }
 
 void RenderWidgetHostViewAndroid::OnDidNavigateMainFrameToNewPage() {
@@ -1263,11 +1277,10 @@ void RenderWidgetHostViewAndroid::OnSelectionEvent(
     ui::SelectionEventType event) {
   DCHECK(content_view_core_);
   DCHECK(selection_controller_);
-  // Showing the selection action bar can alter the current View coordinates in
-  // such a way that the current MotionEvent stream is suddenly shifted in
-  // space. Avoid the associated scroll jump by pre-emptively cancelling gesture
-  // detection; scrolling after the selection is activated is unnecessary.
-  if (event == ui::SelectionEventType::SELECTION_SHOWN)
+  // If a selection drag has started, it has taken over the active touch
+  // sequence. Immediately cancel gesture detection and any downstream touch
+  // listeners (e.g., web content) to communicate this transfer.
+  if (event == ui::SELECTION_SHOWN)
     ResetGestureDetection();
   content_view_core_->OnSelectionEvent(
       event, selection_controller_->GetStartPosition(),
@@ -1531,6 +1544,11 @@ bool RenderWidgetHostViewAndroid::Animate(base::TimeTicks frame_time) {
   return needs_animate;
 }
 
+void RenderWidgetHostViewAndroid::RequestDisallowInterceptTouchEvent() {
+  if (content_view_core_)
+    content_view_core_->RequestDisallowInterceptTouchEvent();
+}
+
 void RenderWidgetHostViewAndroid::EvictDelegatedFrame() {
   if (layer_.get())
     DestroyDelegatedContent();

content/browser/renderer_host/render_widget_host_view_android.h

@@ -323,6 +323,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAndroid
   void StopObservingRootWindow();
   void SendBeginFrame(base::TimeTicks frame_time, base::TimeDelta vsync_period);
   bool Animate(base::TimeTicks frame_time);
+  void RequestDisallowInterceptTouchEvent();
 
   // The model object.
   RenderWidgetHostImpl* host_;

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

@@ -1189,6 +1189,11 @@ public class ContentViewCore implements
         }
     }
 
+    @CalledByNative
+    private void requestDisallowInterceptTouchEvent() {
+        mContainerView.requestDisallowInterceptTouchEvent(true);
+    }
+
     private static boolean isValidTouchEventActionForNative(int eventAction) {
         // Only these actions have any effect on gesture detection.  Other
         // actions have no corresponding WebTouchEvent type and may confuse the