aura: Don't synthesize mouse move or exit events during shutdown

This simplifies teardown, especially in ash on Chrome OS.

Also add tests for the code in crrev.com/c/1180070 which generally
skips event dispatch during shutdown.

Bug: 874156
Test: added to aura_unittests
Change-Id: I1356c3a1ab09f07d23dca1545d3159fcc4016e2d
Reviewed-on: https://chromium-review.googlesource.com/1181537Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585324}

ui/aura/window_event_dispatcher.cc

@@ -861,7 +861,7 @@ ui::EventDispatchDetails WindowEventDispatcher::DispatchHeldEvents() {
 }
 
 void WindowEventDispatcher::PostSynthesizeMouseMove() {
-  if (synthesize_mouse_move_)
+  if (synthesize_mouse_move_ || in_shutdown_)
     return;
   synthesize_mouse_move_ = true;
   base::ThreadTaskRunnerHandle::Get()->PostNonNestableTask(
@@ -873,6 +873,8 @@ void WindowEventDispatcher::PostSynthesizeMouseMove() {
 
 void WindowEventDispatcher::SynthesizeMouseMoveAfterChangeToWindow(
     Window* window) {
+  if (in_shutdown_)
+    return;
   if (window->IsVisible() &&
       window->ContainsPointInRoot(GetLastMouseLocationInRoot())) {
     PostSynthesizeMouseMove();
@@ -881,7 +883,7 @@ void WindowEventDispatcher::SynthesizeMouseMoveAfterChangeToWindow(
 
 ui::EventDispatchDetails WindowEventDispatcher::SynthesizeMouseMoveEvent() {
   DispatchDetails details;
-  if (!synthesize_mouse_move_)
+  if (!synthesize_mouse_move_ || in_shutdown_)
     return details;
   synthesize_mouse_move_ = false;
 

ui/aura/window_event_dispatcher.h

@@ -64,6 +64,7 @@ class AURA_EXPORT WindowEventDispatcher : public ui::EventProcessor,
   WindowEventDispatcher(WindowTreeHost* host, bool are_events_in_pixels);
   ~WindowEventDispatcher() override;
 
+  // Stops dispatching/synthesizing mouse events.
   void Shutdown();
 
   WindowTreeHost* host() { return host_; }

ui/aura/window_event_dispatcher_unittest.cc

@@ -940,6 +940,31 @@ TEST_P(WindowEventDispatcherTest, DispatchMouseExitWhenHidingWindow) {
             recorder.mouse_locations()[0].ToString());
 }
 
+// Tests that a mouse-exit event is not synthesized during shutdown.
+TEST_P(WindowEventDispatcherTest, NoMouseExitInShutdown) {
+  EventFilterRecorder recorder;
+  test::TestWindowDelegate delegate;
+  std::unique_ptr<aura::Window> window(CreateTestWindowWithDelegate(
+      &delegate, 1, gfx::Rect(10, 10, 50, 50), root_window()));
+  window->Show();
+  window->AddPreTargetHandler(&recorder);
+
+  // Simulate mouse move into the window.
+  const gfx::Point event_location = window->bounds().CenterPoint();
+  ui::MouseEvent mouse(ui::ET_MOUSE_MOVED, event_location, event_location,
+                       ui::EventTimeForNow(), 0, 0);
+  DispatchEventUsingWindowDispatcher(&mouse);
+  EXPECT_FALSE(recorder.events().empty());
+  recorder.Reset();
+
+  // Simulate shutdown.
+  host()->dispatcher()->Shutdown();
+
+  // Hiding the window does not generate a mouse-exit event.
+  window->Hide();
+  EXPECT_TRUE(recorder.events().empty());
+}
+
 // Verifies that a direct call to ProcessedTouchEvent() does not cause a crash.
 TEST_P(WindowEventDispatcherTest, CallToProcessedTouchEvent) {
   test::TestWindowDelegate delegate;
@@ -1118,6 +1143,29 @@ TEST_P(WindowEventDispatcherTest, DoNotSynthesizeWhileButtonDown) {
   root_window()->RemovePreTargetHandler(&recorder);
 }
 
+// Tests that a mouse-press event is not dispatched during shutdown.
+TEST_P(WindowEventDispatcherTest, DoNotDispatchInShutdown) {
+  EventFilterRecorder recorder;
+  test::TestWindowDelegate delegate;
+  std::unique_ptr<aura::Window> window(CreateTestWindowWithDelegate(
+      &delegate, 1234, gfx::Rect(5, 5, 100, 100), root_window()));
+  window->Show();
+  window->AddPreTargetHandler(&recorder);
+
+  // Simulate shutdown.
+  host()->dispatcher()->Shutdown();
+
+  // Attempt to dispatch a mouse press.
+  const gfx::Point center = window->bounds().CenterPoint();
+  ui::MouseEvent press(ui::ET_MOUSE_PRESSED, center, center,
+                       ui::EventTimeForNow(), ui::EF_LEFT_MOUSE_BUTTON,
+                       ui::EF_LEFT_MOUSE_BUTTON);
+  DispatchEventUsingWindowDispatcher(&press);
+
+  // Event was not dispatched.
+  EXPECT_TRUE(recorder.events().empty());
+}
+
 #if defined(OS_WIN) && defined(ARCH_CPU_X86)
 #define MAYBE(x) DISABLED_##x
 #else