exo: Replace fling cancel with generic zero distance scroll

components/exo/pointer.cc

 // Copyright 2015 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 "components/exo/pointer.h"
 
 #include "ash/display/display_manager.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "components/exo/pointer_delegate.h"
 #include "components/exo/pointer_stylus_delegate.h"
@@ skipping 229 matching lines @@
         delegate_->OnPointerFrame();
       }
       break;
     case ui::ET_SCROLL_FLING_START:
       if (focus_) {
         delegate_->OnPointerScrollStop(event->time_stamp());
         delegate_->OnPointerFrame();
       }
       break;
     case ui::ET_SCROLL_FLING_CANCEL:
-      if (focus_) {
-        delegate_->OnPointerScrollCancel(event->time_stamp());
+      if (focus_ && last_event_type_ == ui::ET_SCROLL_FLING_START) {
+        delegate_->OnPointerScroll(event->time_stamp(), gfx::Vector2dF(),
+                                   false);
+        delegate_->OnPointerFrame();
+        delegate_->OnPointerScrollStop(event->time_stamp());
         delegate_->OnPointerFrame();
       }
       break;
     case ui::ET_MOUSE_MOVED:
     case ui::ET_MOUSE_DRAGGED:
     case ui::ET_MOUSE_ENTERED:
     case ui::ET_MOUSE_EXITED:
     case ui::ET_MOUSE_CAPTURE_CHANGED:
       break;
     default:
       NOTREACHED();
       break;
   }
 
-  if ((event->flags() & ui::EF_IS_SYNTHESIZED) == 0)
-    is_direct_input_ = (event->flags() & ui::EF_DIRECT_INPUT) != 0;
+  if (!(event->flags() & ui::EF_IS_SYNTHESIZED)) {
+    is_direct_input_ = event->flags() & ui::EF_DIRECT_INPUT;
+    last_event_type_ = event->type();
+  }
 
   // Update cursor widget to reflect current focus and pointer location.
   if (focus_ && !is_direct_input_) {
     if (!widget_)
       CreatePointerWidget();
 
     // Update cursor location if mouse event caused it to change.
     gfx::Point mouse_location = aura::Env::GetInstance()->last_mouse_location();
     gfx::Rect bounds = widget_->GetWindowBoundsInScreen();
     if (mouse_location != bounds.origin()) {
@@ skipping 91 matching lines @@
 
   if (ui_scale != cursor_scale_) {
     gfx::Transform transform;
     transform.Scale(ui_scale, ui_scale);
     widget_->GetNativeWindow()->SetTransform(transform);
     cursor_scale_ = ui_scale;
   }
 }
 
 }  // namespace exo