send mousemove instead of leave after context menu

This CL changes mac SetShowingContextMenu to send a MouseMove instead
of MouseLeave. And add kRelativeMotionEvent flag in the modifier to
avoid sending the event to DOM.
Sending MouseLeave will cause hover/active state be cleared when open
contextmenu.

Bug: 803844
Change-Id: I38f2864b108f95a51c6e93536a1b410333fdf50e
Reviewed-on: https://chromium-review.googlesource.com/888092Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Commit-Queue: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532931}

content/browser/renderer_host/render_widget_host_view_mac.mm

@@ -1161,8 +1161,8 @@ void RenderWidgetHostViewMac::SetShowingContextMenu(bool showing) {
                                     clickCount:0
                                       pressure:0];
   WebMouseEvent web_event = WebMouseEventBuilder::Build(event, cocoa_view_);
-  if (showing)
-    web_event.SetType(WebInputEvent::kMouseLeave);
+  web_event.SetModifiers(web_event.GetModifiers() |
+                         WebInputEvent::kRelativeMotionEvent);
   ForwardMouseEvent(web_event);
 }
 

content/browser/renderer_host/render_widget_host_view_mac_unittest.mm

@@ -1111,6 +1111,21 @@ TEST_F(RenderWidgetHostViewMacTest, PointerEventWithMouseType) {
             GetPointerType(events));
 }
 
+TEST_F(RenderWidgetHostViewMacTest, SendMouseMoveOnShowingContextMenu) {
+  rwhv_mac_->SetShowingContextMenu(true);
+  base::RunLoop().RunUntilIdle();
+  MockWidgetInputHandler::MessageVector events =
+      host_->GetAndResetDispatchedMessages();
+  ASSERT_EQ("MouseMove", GetMessageNames(events));
+
+  events.clear();
+
+  rwhv_mac_->SetShowingContextMenu(false);
+  base::RunLoop().RunUntilIdle();
+  events = host_->GetAndResetDispatchedMessages();
+  ASSERT_EQ("MouseMove", GetMessageNames(events));
+}
+
 void RenderWidgetHostViewMacTest::
     IgnoreEmptyUnhandledWheelEventWithWheelGestures() {
   // Add a delegate to the view.