GSB uses delta_hints to calculate scrolling chain.

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 d90ce9970179b993d62b17c5faa0e0b5957a246d..c675245528bda6fc2058dec307ffb17d9ec4bf92 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -830,7 +830,7 @@ TEST_F(LayerTreeHostImplTest, ScrollRootCallsCommitAndRedraw) {
 
   host_impl_->SetViewportSize(gfx::Size(50, 50));
   DrawFrame();
-
+  LOG(ERROR) << "Scroll begin";
   InputHandler::ScrollStatus status = host_impl_->ScrollBegin(
       BeginState(gfx::Point()).get(), InputHandler::WHEEL);
   EXPECT_EQ(InputHandler::SCROLL_ON_IMPL_THREAD, status.thread);
@@ -839,9 +839,11 @@ TEST_F(LayerTreeHostImplTest, ScrollRootCallsCommitAndRedraw) {
 
   EXPECT_TRUE(host_impl_->IsCurrentlyScrollingLayerAt(gfx::Point(),
                                                       InputHandler::WHEEL));
+  LOG(ERROR) << "SCroll By";
   host_impl_->ScrollBy(UpdateState(gfx::Point(), gfx::Vector2d(0, 10)).get());
   EXPECT_TRUE(host_impl_->IsCurrentlyScrollingLayerAt(gfx::Point(0, 10),
                                                       InputHandler::WHEEL));
+  LOG(ERROR) << "scroll end";
   host_impl_->ScrollEnd(EndState().get());
   EXPECT_FALSE(host_impl_->IsCurrentlyScrollingLayerAt(gfx::Point(),
                                                        InputHandler::WHEEL));
@@ -6049,12 +6051,15 @@ TEST_F(LayerTreeHostImplTest, ScrollNonAxisAlignedRotatedLayer) {
     // Now reset and scroll the same amount horizontally.
     SetScrollOffsetDelta(child_ptr, gfx::Vector2dF());
     gfx::Vector2d gesture_scroll_delta(10, 0);
+    LOG(ERROR) << "scroll begin:\n";
     EXPECT_EQ(InputHandler::SCROLL_ON_IMPL_THREAD,
               host_impl_
-                  ->ScrollBegin(BeginState(gfx::Point(1, 1)).get(),
+                  ->ScrollBegin(BeginState(gfx::Point()).get(),
                                 InputHandler::TOUCHSCREEN)
                   .thread);
+    LOG(ERROR) << "\nscroll by:\n";
     host_impl_->ScrollBy(UpdateState(gfx::Point(), gesture_scroll_delta).get());
+    LOG(ERROR) << "\nscroll begin:\n";
     host_impl_->ScrollEnd(EndState().get());
 
     // The child layer shouldn't have scrolled.
@@ -9760,6 +9765,7 @@ TEST_F(LayerTreeHostImplWithBrowserControlsTest,
       BOTH, SHOWN, false);
   DrawFrame();
 
+  LOG(ERROR) << "\nscroll begin:\n";
   EXPECT_EQ(InputHandler::SCROLL_ON_IMPL_THREAD,
             host_impl_
                 ->ScrollBegin(BeginState(gfx::Point()).get(),
@@ -9768,6 +9774,7 @@ TEST_F(LayerTreeHostImplWithBrowserControlsTest,
   EXPECT_EQ(0, host_impl_->browser_controls_manager()->ControlsTopOffset());
 
   float offset = 50;
+  LOG(ERROR) << "\nscroll by 1:\n";
   EXPECT_TRUE(
       host_impl_
           ->ScrollBy(UpdateState(gfx::Point(), gfx::Vector2d(0, offset)).get())
@@ -9776,14 +9783,14 @@ TEST_F(LayerTreeHostImplWithBrowserControlsTest,
             host_impl_->browser_controls_manager()->ControlsTopOffset());
   EXPECT_EQ(gfx::Vector2dF().ToString(),
             scroll_layer->CurrentScrollOffset().ToString());
-
+  LOG(ERROR) << "\nscroll by 2:\n";
   EXPECT_TRUE(
       host_impl_
           ->ScrollBy(UpdateState(gfx::Point(), gfx::Vector2d(0, offset)).get())
           .did_scroll);
   EXPECT_EQ(gfx::Vector2dF(0, offset).ToString(),
             scroll_layer->CurrentScrollOffset().ToString());
-
+  LOG(ERROR) << "\nscroll by 3:\n";
   EXPECT_TRUE(
       host_impl_
           ->ScrollBy(UpdateState(gfx::Point(), gfx::Vector2d(0, offset)).get())
@@ -9794,7 +9801,7 @@ TEST_F(LayerTreeHostImplWithBrowserControlsTest,
             scroll_layer->CurrentScrollOffset().ToString());
 
   float overscrollamount = 10;
-
+  LOG(ERROR) << "\nscroll by 4:\n";
   // Overscroll the content
   EXPECT_FALSE(host_impl_
                    ->ScrollBy(UpdateState(gfx::Point(),
@@ -9805,7 +9812,7 @@ TEST_F(LayerTreeHostImplWithBrowserControlsTest,
             scroll_layer->CurrentScrollOffset().ToString());
   EXPECT_EQ(gfx::Vector2dF(0, overscrollamount).ToString(),
             host_impl_->accumulated_root_overscroll().ToString());
-
+  LOG(ERROR) << "\nscroll by 5:\n";
   EXPECT_TRUE(
       host_impl_
           ->ScrollBy(
@@ -9815,7 +9822,7 @@ TEST_F(LayerTreeHostImplWithBrowserControlsTest,
             scroll_layer->CurrentScrollOffset().ToString());
   EXPECT_EQ(-offset,
             host_impl_->browser_controls_manager()->ControlsTopOffset());
-
+  LOG(ERROR) << "\nscroll by 6:\n";
   EXPECT_TRUE(
       host_impl_
           ->ScrollBy(UpdateState(gfx::Point(), gfx::Vector2d(0, -offset)).get())
@@ -9825,7 +9832,7 @@ TEST_F(LayerTreeHostImplWithBrowserControlsTest,
 
   // Browser controls should be fully visible
   EXPECT_EQ(0, host_impl_->browser_controls_manager()->ControlsTopOffset());
-
+  LOG(ERROR) << "\nscroll end:\n";
   host_impl_->ScrollEnd(EndState().get());
 }
 
@@ -10826,12 +10833,14 @@ TEST_F(LayerTreeHostImplTest, SecondScrollAnimatedBeginNotIgnored) {
   const gfx::Size viewport_size(50, 100);
   CreateBasicVirtualViewportLayers(viewport_size, content_size);
 
-  EXPECT_EQ(InputHandler::SCROLL_ON_IMPL_THREAD,
-            host_impl_->ScrollAnimatedBegin(gfx::Point()).thread);
+  EXPECT_EQ(
+      InputHandler::SCROLL_ON_IMPL_THREAD,
+      host_impl_->ScrollAnimatedBegin(BeginState(gfx::Point()).get()).thread);
 
   // The second ScrollAnimatedBegin should not get ignored.
-  EXPECT_EQ(InputHandler::SCROLL_ON_IMPL_THREAD,
-            host_impl_->ScrollAnimatedBegin(gfx::Point()).thread);
+  EXPECT_EQ(
+      InputHandler::SCROLL_ON_IMPL_THREAD,
+      host_impl_->ScrollAnimatedBegin(BeginState(gfx::Point()).get()).thread);
 }
 
 // Verfify that a smooth scroll animation doesn't jump when UpdateTarget gets