Remove is_fling flag for fling intervention

ui/events/blink/input_handler_proxy.cc

 // Copyright 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 "ui/events/blink/input_handler_proxy.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 794 matching lines @@
       return DID_HANDLE;
     }
     case cc::InputHandler::SCROLL_UNKNOWN:
     case cc::InputHandler::SCROLL_ON_MAIN_THREAD: {
       TRACE_EVENT_INSTANT0("input,rail",
                            "InputHandlerProxy::HandleGestureFling::"
                            "scroll_on_main_thread",
                            TRACE_EVENT_SCOPE_THREAD);
       gesture_scroll_on_impl_thread_ = false;
       fling_may_be_active_on_main_thread_ = true;
-      client_->DidStartFlinging();
       return DID_NOT_HANDLE;
     }
     case cc::InputHandler::SCROLL_IGNORED: {
       TRACE_EVENT_INSTANT0(
           "input,rail",
           "InputHandlerProxy::HandleGestureFling::ignored",
           TRACE_EVENT_SCOPE_THREAD);
       gesture_scroll_on_impl_thread_ = false;
       if (gesture_event.sourceDevice == blink::WebGestureDeviceTouchpad) {
         // We still pass the curve to the main thread if there's nothing
@@ skipping 59 matching lines @@
   // we may not want to discard the entire touch sequence. Note this
   // code is explicitly after the assignment of the |touch_start_result_|
   // so the touch moves are not sent to the main thread un-necessarily.
   if (result == DROP_EVENT &&
       input_handler_->GetEventListenerProperties(
           cc::EventListenerClass::kTouchEndOrCancel) !=
           cc::EventListenerProperties::kNone) {
     result = DID_HANDLE_NON_BLOCKING;
   }
 
+  bool is_fling_on_impl = fling_curve_ && !fling_may_be_active_on_main_thread_;
+  if (result == DID_NOT_HANDLE && is_fling_on_impl)
+    result = DID_NOT_HANDLE_NON_BLOCKING_DUE_TO_FLING;
+
   return result;
 }
 
 InputHandlerProxy::EventDisposition InputHandlerProxy::HandleTouchMove(
     const blink::WebTouchEvent& touch_event) {
   if (touch_start_result_ != kEventDispositionUndefined)
     return static_cast<EventDisposition>(touch_start_result_);
   return DID_NOT_HANDLE;
 }
 
@@ skipping 415 matching lines @@
                            "InputHandlerProxy::scrollBy::AbortFling",
                            TRACE_EVENT_SCOPE_THREAD);
       // If we got a DID_NOT_HANDLE, that means we need to deliver wheels on the
       // main thread. In this case we need to schedule a commit and transfer the
       // fling curve over to the main thread and run the rest of the wheels from
       // there. This can happen when flinging a page that contains a scrollable
       // subarea that we can't scroll on the thread if the fling starts outside
       // the subarea but then is flung "under" the pointer.
       client_->TransferActiveWheelFlingAnimation(fling_parameters_);
       fling_may_be_active_on_main_thread_ = true;
-      client_->DidStartFlinging();
       CancelCurrentFlingWithoutNotifyingClient();
       break;
+    case DID_NOT_HANDLE_NON_BLOCKING_DUE_TO_FLING:
+      NOTREACHED();
+      return false;
   }
 
   return false;
 }
 
 bool InputHandlerProxy::scrollBy(const WebFloatSize& increment,
                                  const WebFloatSize& velocity) {
   WebFloatSize clipped_increment;
   WebFloatSize clipped_velocity;
   if (!disallow_horizontal_fling_scroll_) {
@@ skipping 68 matching lines @@
   // is made asynchronously, to minimize divergence between main thread and
   // impl thread event handling paths.
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
       base::Bind(&InputScrollElasticityController::ObserveGestureEventAndResult,
                  scroll_elasticity_controller_->GetWeakPtr(), gesture_event,
                  scroll_result));
 }
 
 }  // namespace ui