Animated scroll shouldn't consume unhandled scrolls for OOPIFs.

content/browser/renderer_host/render_widget_host_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 278 matching lines @@
 
   // Notifies the RenderWidget that it lost the mouse lock.
   void SendMouseLockLost();
 
   // Noifies the RenderWidget of the current mouse cursor visibility state.
   void SendCursorVisibilityState(bool is_visible);
 
   // Notifies the RenderWidgetHost that the View was destroyed.
   void ViewDestroyed();
 
-  // Signals if this host has forwarded a GestureScrollBegin without yet having
-  // forwarded a matching GestureScrollEnd/GestureFlingStart.
-  bool is_in_touchscreen_gesture_scroll() const {
-    return is_in_touchscreen_gesture_scroll_;
-  }
-
 #if defined(OS_MACOSX)
   // Pause for a moment to wait for pending repaint or resize messages sent to
   // the renderer to arrive. If pending resize messages are for an old window
   // size, then also pump through a new resize message if there is time.
   void PauseForPendingResizeOrRepaints();
 
   // Whether pausing may be useful.
   bool CanPauseForPendingResizeOrRepaints();
 
   // Wait for a surface matching the size of the widget's view, possibly
@@ skipping 36 matching lines @@
   virtual void ForwardTouchEventWithLatencyInfo(
       const blink::WebTouchEvent& touch_event,
       const ui::LatencyInfo& ui_latency);  // Virtual for testing.
   void ForwardMouseEventWithLatencyInfo(
       const blink::WebMouseEvent& mouse_event,
       const ui::LatencyInfo& ui_latency);
   virtual void ForwardWheelEventWithLatencyInfo(
       const blink::WebMouseWheelEvent& wheel_event,
       const ui::LatencyInfo& ui_latency);  // Virtual for testing.
 
+  // Signals if this host has forwarded a GestureScrollBegin without yet having
+  // forwarded a matching GestureScrollEnd/GestureFlingStart.
+  bool is_in_gesture_scroll(blink::WebGestureDevice device) override;

[bokan, 2017/04/11 16:23:14]

Touchscreen and Touchpad gesture event streams can differ for Flings but I can
never remember how. Sahel should confirm that this change is ok.

[sahel, 2017/04/12 15:40:22]

This function is used only for wheel/touchpad scrolling. For 4 combinations of
existence of OOPIFs and scroll propagation vs latching, this logic works for all
except the case that an OOPIF exists and scroll latching is enabled. This case
is broken anyway and regardless of this change we need to fix it.

Touchpad GFS comes after a GSE when wheel scroll latching is disabled
(is_in_gesture_scroll is false), but when latching is enabled, similar to touch,
GFS comes when is_in_gesture_scroll is true. In all cases GFS sets
is_in_gesture_scroll to false.

[bokan, 2017/04/12 19:15:10]

I don't think that's true. Taking a quick look, it was and still is called from
RenderWidgetHostInputEventRouter::RouteTouchscreenGestureEvent.

[sahel, 2017/04/18 15:43:43]

I think is_in_touchscreen_gesture_scroll() is called in
RenderWidgetHostInputEventRouter::RouteTouchscreenGestureEvent rather than
is_in_gesture_scroll(). Maybe it should be changed to this new function, though.

+
   // Enables/disables touch emulation using mouse event. See TouchEmulator.
   void SetTouchEventEmulationEnabled(
       bool enabled, ui::GestureProviderConfigType config_type);
 
   // TouchEmulatorClient implementation.
   void ForwardEmulatedGestureEvent(
       const blink::WebGestureEvent& gesture_event) override;
   void ForwardEmulatedTouchEvent(
       const blink::WebTouchEvent& touch_event) override;
   void SetCursor(const WebCursor& cursor) override;
@@ skipping 603 matching lines @@
   std::queue<std::pair<uint32_t, std::vector<IPC::Message>>> queued_messages_;
 
   base::WeakPtrFactory<RenderWidgetHostImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_IMPL_H_