Suppress ET_MOUSE_MOVE when the mouse hasn't moved on Windows.

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 eb6449f0c8996436534491c40ce5542f4c6c6d3e..5b940bfb9ceb5b5485fc6385e917062afb5724ce 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -217,6 +217,34 @@ void EmbedCallback(bool result) {
     DVLOG(1) << "embed failed";
 }
 
+// We need to watch for mouse events outside a Web Popup or its parent
+// and dismiss the popup for certain events.
+class EventFilterForMouseMove : public ui::EventHandler {
+ public:
+  EventFilterForMouseMove() {
+    aura::Env::GetInstance()->AddPreTargetHandler(this);

[sadrul, 2017/01/27 00:22:03]

This should install the event-handler on the RWHVA's |window_|.

... although, why not remember the last location in RWHVA::OnMouseEvent without
installing any pre-target handlers at all?

+  }
+
+  ~EventFilterForMouseMove() override {
+    aura::Env::GetInstance()->RemovePreTargetHandler(this);
+  }
+
+  // Overridden from ui::EventHandler
+  void OnMouseEvent(ui::MouseEvent* event) override {
+    if (event->type() != ui::ET_MOUSE_MOVED)
+      return;
+    if (event->location() == last_location_) {
+      event->SetHandled();
+      return;
+    }
+    last_location_ = event->location();
+  }
+
+ private:
+  gfx::Point last_location_;
+  DISALLOW_COPY_AND_ASSIGN(EventFilterForMouseMove);
+};
+
 }  // namespace
 
 // We need to watch for mouse events outside a Web Popup or its parent
@@ -420,6 +448,13 @@ RenderWidgetHostViewAura::RenderWidgetHostViewAura(RenderWidgetHost* host,
     // first to rebaseline some unreliable layout tests.
     ignore_result(rvh->GetWebkitPreferences());
   }
+
+#if defined(OS_WIN)
+  // Windows will post a WM_MOUSEMOVE after a click event. Other platforms
+  // do not do this so we filter out mouse moves where the position doesn't
+  // change from the last event.
+  event_filter_for_mouse_move_.reset(new EventFilterForMouseMove());
+#endif
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1853,6 +1888,8 @@ RenderWidgetHostViewAura::~RenderWidgetHostViewAura() {
   event_filter_for_popup_exit_.reset();
 
 #if defined(OS_WIN)
+  event_filter_for_mouse_move_.reset();
+
   // The LegacyRenderWidgetHostHWND window should have been destroyed in
   // RenderWidgetHostViewAura::OnWindowDestroying and the pointer should
   // be set to NULL.