Improve test coverage of unused scroll delta for cc scrolling.

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 6ded33b16745bab43c6faab2891ad474a00d78a7..d084c9c1c38e15e66e9c0ebb5a6c585db43ce046 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -7018,6 +7018,7 @@ TEST_F(LayerTreeHostImplWithTopControlsTest, TopControlsAnimationScheduling) {
 }
 
 TEST_F(LayerTreeHostImplWithTopControlsTest, ScrollHandledByTopControls) {
+  InputHandlerScrollResult result;
   LayerImpl* scroll_layer = SetupScrollAndContentsLayers(gfx::Size(100, 200));
   host_impl_->SetViewportSize(gfx::Size(100, 100));
   host_impl_->top_controls_manager()->UpdateTopControlsState(
@@ -7033,8 +7034,9 @@ TEST_F(LayerTreeHostImplWithTopControlsTest, ScrollHandledByTopControls) {
   // Scroll just the top controls and verify that the scroll succeeds.
   const float residue = 10;
   float offset = top_controls_height_ - residue;
-  EXPECT_TRUE(
-      host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset)).did_scroll);
+  result = host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset));
+  EXPECT_EQ(result.unused_scroll_delta, gfx::Vector2d(0, 0));
+  EXPECT_TRUE(result.did_scroll);
   EXPECT_FLOAT_EQ(-offset,
                   host_impl_->top_controls_manager()->ControlsTopOffset());
   EXPECT_EQ(gfx::Vector2dF().ToString(),
@@ -7043,8 +7045,9 @@ TEST_F(LayerTreeHostImplWithTopControlsTest, ScrollHandledByTopControls) {
   // Scroll across the boundary
   const float content_scroll = 20;
   offset = residue + content_scroll;
-  EXPECT_TRUE(
-      host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset)).did_scroll);
+  result = host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset));
+  EXPECT_TRUE(result.did_scroll);
+  EXPECT_EQ(result.unused_scroll_delta, gfx::Vector2d(0, 0));
   EXPECT_EQ(-top_controls_height_,
             host_impl_->top_controls_manager()->ControlsTopOffset());
   EXPECT_EQ(gfx::Vector2dF(0, content_scroll).ToString(),
@@ -7052,8 +7055,9 @@ TEST_F(LayerTreeHostImplWithTopControlsTest, ScrollHandledByTopControls) {
 
   // Now scroll back to the top of the content
   offset = -content_scroll;
-  EXPECT_TRUE(
-      host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset)).did_scroll);
+  result = host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset));
+  EXPECT_TRUE(result.did_scroll);
+  EXPECT_EQ(result.unused_scroll_delta, gfx::Vector2d(0, 0));
   EXPECT_EQ(-top_controls_height_,
             host_impl_->top_controls_manager()->ControlsTopOffset());
   EXPECT_EQ(gfx::Vector2dF().ToString(),
@@ -7061,15 +7065,17 @@ TEST_F(LayerTreeHostImplWithTopControlsTest, ScrollHandledByTopControls) {
 
   // And scroll the top controls completely into view
   offset = -top_controls_height_;
-  EXPECT_TRUE(
-      host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset)).did_scroll);
+  result = host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset));
+  EXPECT_TRUE(result.did_scroll);
+  EXPECT_EQ(result.unused_scroll_delta, gfx::Vector2d(0, 0));
   EXPECT_EQ(0, host_impl_->top_controls_manager()->ControlsTopOffset());
   EXPECT_EQ(gfx::Vector2dF().ToString(),
             scroll_layer->CurrentScrollOffset().ToString());
 
   // And attempt to scroll past the end
-  EXPECT_FALSE(
-      host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset)).did_scroll);
+  result = host_impl_->ScrollBy(gfx::Point(), gfx::Vector2d(0, offset));
+  EXPECT_FALSE(result.did_scroll);
+  EXPECT_EQ(result.unused_scroll_delta, gfx::Vector2d(0, -50));
   EXPECT_EQ(0, host_impl_->top_controls_manager()->ControlsTopOffset());
   EXPECT_EQ(gfx::Vector2dF().ToString(),
             scroll_layer->CurrentScrollOffset().ToString());