Avoid unnecessary gloweffect calls

cc/trees/layer_tree_host_impl_unittest.cc

Index: cc/trees/layer_tree_host_impl_unittest.cc
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 37f2cd551c368aeed47343097219b9e62fc28553..59d819b29ade4c96e8078fd3336472ca2a79718a 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -3162,6 +3162,42 @@ TEST_F(LayerTreeHostImplTest, OverscrollAlways) {
   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,