Suppress sending mousedown / mouseup when in fling

content/browser/renderer_host/tap_suppression_controller_aura.cc

 // 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.
 
 #include "content/browser/renderer_host/tap_suppression_controller.h"
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
@@ skipping 114 matching lines @@
     case GFC_IN_PROGRESS:
       if (processed)
         fling_cancel_time_ = base::TimeTicks::Now();
       state_ = LAST_CANCEL_STOPPED_FLING;
       break;
     case MD_STASHED:
       if (!processed) {
         TRACE_EVENT0("browser",
                      "TapSuppressionController::GestureFlingCancelAck");
         mouse_down_timer_.Stop();
+        state_ = NOTHING;
         render_widget_host_->ForwardMouseEvent(stashed_mouse_down_);
-        state_ = NOTHING;

[mohsen, 2012/11/21 18:34:54]

If MouseDown is forwarded before setting the state_ to NOTHING, the
ShouldDeferMouseDown() method will be called while state_ is still set to
MD_STASHED, which is not desirable.

[rjkroege, 2012/11/21 20:41:18]

this is indeed an issue. TSC is not tested or intended to be recursive. I would
imagine that there might be other bugs of this kind in the future. I think it
would be better to add a RenderWidgetHostImpl::ForwardMouseEventImmediately
instead?

[mohsen, 2012/11/21 22:11:32]

I agree. The only problem is that most of the code for these two functions
(immediate and non-immediate) would be common. Maybe, we had better factor out
those common parts into another function or call the immediate one from inside
the non-immediate one, if it decides to forward the event. What do you think?

(BTW, I think the best solution is to somehow have a one-way relationship
between RWHI/GEF and TSC, i.e. only RWHI/GEF know of TSC.)

       } // Else waiting for the timer to release the mouse event.
       break;
     case LAST_CANCEL_STOPPED_FLING:
       break;
   }
 }
 
 void TapSuppressionController::GestureFlingCancel(double cancel_time) {
   switch (state_) {
     case NOTHING:
@@ skipping 10 matching lines @@
   switch (state_) {
     case NOTHING:
     case GFC_IN_PROGRESS:
     case LAST_CANCEL_STOPPED_FLING:
       NOTREACHED() << "Timer fired on invalid state.";
       state_ = NOTHING;
       break;
     case MD_STASHED:
       TRACE_EVENT0("browser",
                    "TapSuppressionController::MouseDownTimerExpired");
+      state_ = NOTHING;
       render_widget_host_->ForwardMouseEvent(stashed_mouse_down_);
-      state_ = NOTHING;

[mohsen, 2012/11/21 18:34:54]

The same as note under line 136.

       break;
   }
 }
 
 } // namespace content