aura: Do not synthesize a mouse-move event during a drag.

Synthesizing a mouse-move event during a drag can cause an inconsistent sequence
of events to be dispatched (e.g. pressed, dragged, dragged, moved, dragged ...
released). So do not synthesize mouse-move events when a drag is in progress. The
alternate is to synthesize mouse-dragged event instead of a mouse-move event, but
in multi-display/multi-host setting, the wrong dispatcher may end up synthesizing
the event. So avoid doing that.

BUG=389424, 369247, 366096
R=oshima@chromium.org

Review URL: https://codereview.chromium.org/387863003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282805 0039d316-1c4b-4281-b951-d872f2087c98

ui/aura/window_event_dispatcher.cc

@@ -694,6 +694,15 @@ ui::EventDispatchDetails WindowEventDispatcher::SynthesizeMouseMoveEvent() {
   if (!synthesize_mouse_move_)
     return details;
   synthesize_mouse_move_ = false;
+
+  // If one of the mouse buttons is currently down, then do not synthesize a
+  // mouse-move event. In such cases, aura could synthesize a DRAGGED event
+  // instead of a MOVED event, but in multi-display/multi-host scenarios, the
+  // DRAGGED event can be synthesized in the incorrect host. So avoid
+  // synthesizing any events at all.
+  if (Env::GetInstance()->mouse_button_flags())
+    return details;
+
   gfx::Point root_mouse_location = GetLastMouseLocationInRoot();
   if (!window()->bounds().Contains(root_mouse_location))
     return details;

ui/aura/window_event_dispatcher_unittest.cc

@@ -917,6 +917,34 @@ TEST_F(WindowEventDispatcherTest, DispatchSyntheticMouseEvents) {
   root_window()->RemovePreTargetHandler(&recorder);
 }
 
+// Tests that a mouse-move event is not synthesized when a mouse-button is down.
+TEST_F(WindowEventDispatcherTest, DoNotSynthesizeWhileButtonDown) {
+  EventFilterRecorder recorder;
+  test::TestWindowDelegate delegate;
+  scoped_ptr<aura::Window> window(CreateTestWindowWithDelegate(
+      &delegate, 1234, gfx::Rect(5, 5, 100, 100), root_window()));
+  window->Show();
+
+  window->AddPreTargetHandler(&recorder);
+  // Dispatch a non-synthetic mouse event when mouse events are enabled.
+  ui::MouseEvent mouse1(ui::ET_MOUSE_PRESSED, gfx::Point(10, 10),
+                        gfx::Point(10, 10), ui::EF_LEFT_MOUSE_BUTTON,
+                        ui::EF_LEFT_MOUSE_BUTTON);
+  DispatchEventUsingWindowDispatcher(&mouse1);
+  ASSERT_EQ(1u, recorder.events().size());
+  EXPECT_EQ(ui::ET_MOUSE_PRESSED, recorder.events()[0]);
+  window->RemovePreTargetHandler(&recorder);
+  recorder.Reset();
+
+  // Move |window| away from underneath the cursor.
+  root_window()->AddPreTargetHandler(&recorder);
+  window->SetBounds(gfx::Rect(30, 30, 100, 100));
+  EXPECT_TRUE(recorder.events().empty());
+  RunAllPendingInMessageLoop();
+  EXPECT_TRUE(recorder.events().empty());
+  root_window()->RemovePreTargetHandler(&recorder);
+}
+
 #if defined(OS_WIN) && defined(ARCH_CPU_X86)
 #define MAYBE(x) DISABLED_##x
 #else