Pass MouseUp to the captured scrollbar animation controller in layer tree

cc/trees/layer_tree_host_impl_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 11691 matching lines @@
       scrollbar_2_animation_controller->mouse_is_over_scrollbar(VERTICAL));
   host_impl_->MouseMoveAt(gfx::Point(10, 150));
   EXPECT_TRUE(
       scrollbar_1_animation_controller->mouse_is_near_scrollbar(VERTICAL));
   EXPECT_TRUE(
       scrollbar_1_animation_controller->mouse_is_over_scrollbar(VERTICAL));
   EXPECT_FALSE(
       scrollbar_2_animation_controller->mouse_is_near_scrollbar(VERTICAL));
   EXPECT_FALSE(
       scrollbar_2_animation_controller->mouse_is_over_scrollbar(VERTICAL));
+
+  // Capture scrollbar_1, then move mouse to scrollbar_2's layer, should post an
+  // event to fade out scrollbar_1.
+  animation_task_ = base::Closure();
+
+  host_impl_->MouseDown();
+  host_impl_->MouseMoveAt(gfx::Point(100, 150));
+  host_impl_->MouseUp();
+
+  EXPECT_FALSE(animation_task_.Equals(base::Closure()));
 }
 
 TEST_F(LayerTreeHostImplTest,
        LayerTreeHostImplTestScrollbarStatesInMainThreadScorlling) {
   SetupMouseMoveAtTestScrollbarStates(true);
 }
 
 TEST_F(LayerTreeHostImplTest,
        LayerTreeHostImplTestScrollbarStatesInNotMainThreadScorlling) {
   SetupMouseMoveAtTestScrollbarStates(false);
 }
 
 }  // namespace
 }  // namespace cc