Avoid unnecessary gloweffect calls

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 3144 matching lines @@
   EXPECT_EQ(gfx::Vector2dF(), host_impl_->current_fling_velocity());
 
   // Even though the layer can't scroll the overscroll still happens.
   EXPECT_EQ(InputHandler::ScrollStarted,
             host_impl_->ScrollBegin(gfx::Point(), InputHandler::Wheel));
   host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, 10));
   EXPECT_EQ(gfx::Vector2dF(0, 10), host_impl_->accumulated_root_overscroll());
   EXPECT_EQ(gfx::Vector2dF(), host_impl_->current_fling_velocity());
 }
 
+TEST_F(LayerTreeHostImplTest, UnnecessaryGlowEffectCallsWhileScrollingUp) {
+  // Edge glow effect should be applicable only upon reaching Edges
+  // of the content. unnecessary glow effect calls shouldn't be
+  // called while scrolling up without reaching the edge of the content.
+  gfx::Size surface_size(100, 100);
+  gfx::Size content_size(200, 200);
+  scoped_ptr<LayerImpl> root_clip =
+      LayerImpl::Create(host_impl_->active_tree(), 3);
+  scoped_ptr<LayerImpl> root =
+      CreateScrollableLayer(1, content_size, root_clip.get());
+  root->SetIsContainerForFixedPositionLayers(true);
+  scoped_ptr<LayerImpl> child =
+      CreateScrollableLayer(2, content_size, root_clip.get());
+
+  child->SetScrollClipLayer(Layer::INVALID_ID);
+  root->AddChild(child.Pass());
+  root_clip->AddChild(root.Pass());
+
+  host_impl_->SetViewportSize(surface_size);
+  host_impl_->active_tree()->SetRootLayer(root_clip.Pass());
+  host_impl_->active_tree()->SetViewportLayersFromIds(3, 1, Layer::INVALID_ID);
+  host_impl_->active_tree()->DidBecomeActive();
+  DrawFrame();
+  {
+    EXPECT_EQ(InputHandler::ScrollStarted,
+              host_impl_->ScrollBegin(gfx::Point(0, 0), InputHandler::Wheel));
+    host_impl_->ScrollBy(gfx::Point(), gfx::Vector2dF(0, 100));
+    EXPECT_EQ(gfx::Vector2dF().ToString(),
+              host_impl_->accumulated_root_overscroll().ToString());
+    host_impl_->ScrollBy(gfx::Point(), gfx::Vector2dF(0, -2.30f));
+    EXPECT_EQ(gfx::Vector2dF().ToString(),
+              host_impl_->accumulated_root_overscroll().ToString());
+    host_impl_->ScrollEnd();
+  }
+}
+
 class BlendStateCheckLayer : public LayerImpl {
  public:
   static scoped_ptr<LayerImpl> Create(LayerTreeImpl* tree_impl,
                                       int id,
                                       ResourceProvider* resource_provider) {
     return scoped_ptr<LayerImpl>(new BlendStateCheckLayer(tree_impl,
                                                           id,
                                                           resource_provider));
   }
 
@@ skipping 3030 matching lines @@
   EXPECT_EQ(host_impl_->global_tile_state().hard_memory_limit_in_bytes,
             300u * 1024u * 1024u);
   EXPECT_EQ(host_impl_->global_tile_state().soft_memory_limit_in_bytes,
             150u * 1024u * 1024u);
   EXPECT_EQ(host_impl_->global_tile_state().unused_memory_limit_in_bytes,
             75u * 1024u * 1024u);
 }
 
 }  // namespace
 }  // namespace cc