Suppress scrolls that begin on fixed-pos layers.

content/renderer/gpu/input_handler_proxy.cc

 // Copyright (c) 2013 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.
 
 #include "content/renderer/gpu/input_handler_proxy.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "content/renderer/gpu/input_handler_proxy_client.h"
@@ skipping 42 matching lines @@
 namespace content {
 
 InputHandlerProxy::InputHandlerProxy(cc::InputHandler* input_handler)
     : client_(NULL),
       input_handler_(input_handler),
 #ifndef NDEBUG
       expect_scroll_update_end_(false),
       expect_pinch_update_end_(false),
 #endif
       gesture_scroll_on_impl_thread_(false),
+      gesture_scroll_on_main_thread_(false),
       gesture_pinch_on_impl_thread_(false),
       fling_may_be_active_on_main_thread_(false),
       fling_overscrolled_horizontally_(false),
       fling_overscrolled_vertically_(false) {
   input_handler_->BindToClient(this);
 }
 
 InputHandlerProxy::~InputHandlerProxy() {}
 
 void InputHandlerProxy::WillShutdown() {
@@ skipping 70 matching lines @@
     const WebGestureEvent& gesture_event =
         *static_cast<const WebGestureEvent*>(&event);
     cc::InputHandler::ScrollStatus scroll_status = input_handler_->ScrollBegin(
         gfx::Point(gesture_event.x, gesture_event.y),
         cc::InputHandler::Gesture);
     switch (scroll_status) {
       case cc::InputHandler::ScrollStarted:
         gesture_scroll_on_impl_thread_ = true;
         return DID_HANDLE;
       case cc::InputHandler::ScrollOnMainThread:
+        gesture_scroll_on_main_thread_ = true;
         return DID_NOT_HANDLE;
       case cc::InputHandler::ScrollIgnored:
         return DROP_EVENT;
     }
   } else if (event.type == WebInputEvent::GestureScrollUpdate) {
 #ifndef NDEBUG
     DCHECK(expect_scroll_update_end_);
 #endif
 
+    if (gesture_scroll_on_main_thread_)
+      return DID_NOT_HANDLE;
+
     if (!gesture_scroll_on_impl_thread_ && !gesture_pinch_on_impl_thread_)
-      return DID_NOT_HANDLE;
+      return DROP_EVENT;
 
     const WebGestureEvent& gesture_event =
         *static_cast<const WebGestureEvent*>(&event);
     bool did_scroll = input_handler_->ScrollBy(
         gfx::Point(gesture_event.x, gesture_event.y),
         gfx::Vector2dF(-gesture_event.data.scrollUpdate.deltaX,
                        -gesture_event.data.scrollUpdate.deltaY));
     return did_scroll ? DID_HANDLE : DROP_EVENT;
   } else if (event.type == WebInputEvent::GestureScrollEnd) {
 #ifndef NDEBUG
     DCHECK(expect_scroll_update_end_);
     expect_scroll_update_end_ = false;
 #endif
     input_handler_->ScrollEnd();
 
+    if (gesture_scroll_on_main_thread_) {
+      gesture_scroll_on_main_thread_ = false;
+      return DID_NOT_HANDLE;
+    }
+
     if (!gesture_scroll_on_impl_thread_)
-      return DID_NOT_HANDLE;
+      return DROP_EVENT;
 
     gesture_scroll_on_impl_thread_ = false;
     return DID_HANDLE;
   } else if (event.type == WebInputEvent::GesturePinchBegin) {
 #ifndef NDEBUG
     DCHECK(!expect_pinch_update_end_);
     expect_pinch_update_end_ = true;
 #endif
     input_handler_->PinchGestureBegin();
     gesture_pinch_on_impl_thread_ = true;
@@ skipping 46 matching lines @@
 InputHandlerProxy::EventDisposition
 InputHandlerProxy::HandleGestureFling(
     const WebGestureEvent& gesture_event) {
   cc::InputHandler::ScrollStatus scroll_status;
 
   if (gesture_event.sourceDevice == WebGestureEvent::Touchpad) {
     scroll_status = input_handler_->ScrollBegin(
         gfx::Point(gesture_event.x, gesture_event.y),
         cc::InputHandler::NonBubblingGesture);
   } else {
-    if (!gesture_scroll_on_impl_thread_)
+    if (gesture_scroll_on_main_thread_)
       scroll_status = cc::InputHandler::ScrollOnMainThread;
     else
       scroll_status = input_handler_->FlingScrollBegin();
   }
 
 #ifndef NDEBUG
   expect_scroll_update_end_ = false;
 #endif
 
   switch (scroll_status) {
@@ skipping 195 matching lines @@
   TRACE_EVENT2("renderer",
                "InputHandlerProxy::notifyCurrentFlingVelocity",
                "vx",
                velocity.width,
                "vy",
                velocity.height);
   input_handler_->NotifyCurrentFlingVelocity(ToClientScrollIncrement(velocity));
 }
 
 }  // namespace content