[Android]Optimization of scrollbar animation.

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 1341 matching lines @@
 
   // If no scroll happened during a scroll gesture, it should have no effect.
   host_impl_->ScrollBegin(gfx::Point(), InputHandler::Wheel);
   host_impl_->ScrollEnd();
   EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
   EXPECT_FALSE(did_request_redraw_);
   EXPECT_TRUE(scrollbar_fade_start_.Equals(base::Closure()));
 
   // 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_->ScrollBy(gfx::Point(), gfx::Vector2dF(0, 5));

[weiliangc, 2014/09/16 16:02:11]

Just want to make sure, why would this fix the test crash? What is the reason
for crash in the first place?

[MuVen, 2014/09/16 16:10:14]

Crash in the sense Expect_LT has failed.Sorry or my confusing english. In this
test Vertical Scrollbar is created and there is scrollby by offset in horizontal
direction, due to which there is no change for vertical scrollbar layer
properties(because of my patch), due to which animation is not triggered and
because of which EXPECT_LT has failed after scrollend.
On 2014/09/16 16:02:11, weiliangc wrote:

   host_impl_->ScrollEnd();
   did_request_redraw_ = false;
   did_request_animate_ = false;
   EXPECT_LT(base::TimeDelta::FromMilliseconds(19),
             requested_scrollbar_animation_delay_);
   EXPECT_FALSE(did_request_redraw_);
   EXPECT_FALSE(did_request_animate_);
   requested_scrollbar_animation_delay_ = base::TimeDelta();
   scrollbar_fade_start_.Run();
   host_impl_->Animate(fake_now);
 
   // After the fade begins, we should start getting redraws instead of a
   // scheduled animation.
   fake_now += base::TimeDelta::FromMilliseconds(25);
   EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
   EXPECT_TRUE(did_request_animate_);
   did_request_animate_ = false;
 
   // Setting the scroll offset outside a scroll should also cause the scrollbar
   // to appear and to schedule a fade.
   host_impl_->InnerViewportScrollLayer()->SetScrollOffset(gfx::Vector2d(5, 5));
   EXPECT_LT(base::TimeDelta::FromMilliseconds(19),
             requested_scrollbar_animation_delay_);
   EXPECT_FALSE(did_request_redraw_);
   EXPECT_FALSE(did_request_animate_);
   requested_scrollbar_animation_delay_ = base::TimeDelta();
+
+  // Unnecessarily Fade animation of solid color scrollbar is not triggered.
+  host_impl_->ScrollBegin(gfx::Point(), InputHandler::Wheel);
+  host_impl_->ScrollBy(gfx::Point(), gfx::Vector2dF(5, 0));
+  host_impl_->ScrollEnd();
+  EXPECT_EQ(base::TimeDelta(), requested_scrollbar_animation_delay_);
 }
 
 TEST_F(LayerTreeHostImplTest, ScrollbarFadePinchZoomScrollbars) {
   LayerTreeSettings settings;
   settings.scrollbar_animator = LayerTreeSettings::LinearFade;
   settings.scrollbar_fade_delay_ms = 20;
   settings.scrollbar_fade_duration_ms = 20;
   settings.use_pinch_zoom_scrollbars = true;
 
   SETUP_LAYERS_FOR_SCROLLBAR_ANIMATION_TEST();
@@ skipping 5713 matching lines @@
   // surface.
   EXPECT_EQ(0, num_lost_surfaces_);
   host_impl_->DidLoseOutputSurface();
   EXPECT_EQ(1, num_lost_surfaces_);
   host_impl_->DidLoseOutputSurface();
   EXPECT_LE(1, num_lost_surfaces_);
 }
 
 }  // namespace
 }  // namespace cc