Suppress scrollbar animation if the scroll gesture does not scroll

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 <cmath>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 1126 matching lines @@
 
   base::TimeTicks fake_now = base::TimeTicks::Now();
   host_impl_override_time->SetCurrentPhysicalTimeTicksForTest(fake_now);
 
   // If no scroll happened recently, StartScrollbarAnimation should have no
   // effect.
   host_impl_->StartScrollbarAnimation();
   EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
   EXPECT_FALSE(did_request_redraw_);
 
+  // If no scroll happened during a scroll gesture, StartScrollbarAnimation
+  // should have no effect.
+  host_impl_->ScrollBegin(gfx::Point(), InputHandler::Wheel);
+  host_impl_->ScrollEnd();
+  host_impl_->StartScrollbarAnimation();
+  EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
+  EXPECT_FALSE(did_request_redraw_);
+
   // After a scroll, a fade animation should be scheduled about 20ms from now.
   host_impl_->ScrollBegin(gfx::Point(), InputHandler::Wheel);
+  host_impl_->ScrollBy(gfx::Point(), gfx::Vector2dF(5, 0));
   host_impl_->ScrollEnd();
+  did_request_redraw_ = false;
   host_impl_->StartScrollbarAnimation();
   EXPECT_LT(base::TimeDelta::FromMilliseconds(19),
             requested_scrollbar_animation_delay_);
   EXPECT_FALSE(did_request_redraw_);
   requested_scrollbar_animation_delay_ = base::TimeDelta();
 
   // After the fade begins, we should start getting redraws instead of a
   // scheduled animation.
   fake_now += base::TimeDelta::FromMilliseconds(25);
   host_impl_override_time->SetCurrentPhysicalTimeTicksForTest(fake_now);
@@ skipping 5339 matching lines @@
   EXPECT_EQ(0u, host_impl_->ResourceIdForUIResource(ui_resource_id));
   EXPECT_EQ(0u, context3d->NumTextures());
 
   // Should not change state for multiple deletion on one UIResourceId
   host_impl_->DeleteUIResource(ui_resource_id);
   EXPECT_EQ(0u, context3d->NumTextures());
 }
 
 }  // namespace
 }  // namespace cc