overscroll-aura: Discard synthetic mouse-move events during a trackpad overscroll.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 4a04d3ab9753db322271e04b48f9ed5eb8394290..1adb873741bbce0414bee46f343363277940258c 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -13,6 +13,7 @@
 #include "base/string_number_conversions.h"
 #include "content/browser/renderer_host/backing_store_aura.h"
 #include "content/browser/renderer_host/dip_util.h"
+#include "content/browser/renderer_host/overscroll_controller.h"
 #include "content/browser/renderer_host/render_view_host_delegate.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/ui_events_helper.h"
@@ -1569,6 +1570,15 @@ ui::EventResult RenderWidgetHostViewAura::OnMouseEvent(ui::MouseEvent* event) {
     return ui::ER_UNHANDLED;
   }
 
+  // If the overscroll controller is active, then drop all synthetic move events
+  // on the floor.

[sky, 2012/11/19 16:25:01]

Document why you do this.

[sadrul, 2012/11/19 16:34:35]

Done.

+  if (host_->overscroll_controller() &&
+      host_->overscroll_controller()->overscroll_mode() != OVERSCROLL_NONE &&
+      event->type() == ui::ET_MOUSE_MOVED &&
+      (event->flags() & ui::EF_IS_SYNTHESIZED)) {
+    return ui::ER_CONSUMED;
+  }
+
   if (event->type() == ui::ET_MOUSEWHEEL) {
     WebKit::WebMouseWheelEvent mouse_wheel_event =
         MakeWebMouseWheelEvent(static_cast<ui::MouseWheelEvent*>(event));