Update from https://crrev.com/320931

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index 94012e0787c5d4781ecaa096d1d378857309f69b..defe796f66d66461042687c1583d1c89ad80c6d1 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -33,12 +33,19 @@
 #include "cc/resources/rasterizer.h"
 #include "cc/resources/resource_provider.h"
 #include "cc/resources/tile_manager.h"
+#include "cc/resources/ui_resource_client.h"
 #include "cc/scheduler/commit_earlyout_reason.h"
 #include "cc/scheduler/draw_result.h"
+#include "cc/trees/layer_tree_settings.h"
+#include "cc/trees/proxy.h"
 #include "skia/ext/refptr.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/geometry/rect.h"
 
+namespace gfx {
+class ScrollOffset;
+}
+
 namespace cc {
 
 class CompletionEvent;
@@ -59,11 +66,13 @@ class RenderingStatsInstrumentation;
 class ResourcePool;
 class ScrollElasticityHelper;
 class ScrollbarLayerImplBase;
+class SwapPromise;
+class SwapPromiseMonitor;
 class TextureMailboxDeleter;
 class TopControlsManager;
 class UIResourceBitmap;
 class UIResourceRequest;
-struct RendererCapabilitiesImpl;
+struct ScrollAndScaleSet;
 
 enum class GpuRasterizationStatus {
   ON,
@@ -593,6 +602,12 @@ class CC_EXPORT LayerTreeHostImpl
   void NotifySwapPromiseMonitorsOfSetNeedsRedraw();
   void NotifySwapPromiseMonitorsOfForwardingToMainThread();
 
+  void ScrollAnimationCreate(LayerImpl* layer_impl,
+                             const gfx::ScrollOffset& target_offset,
+                             const gfx::ScrollOffset& current_offset);
+  bool ScrollAnimationUpdateTarget(LayerImpl* layer_impl,
+                                   const gfx::Vector2dF& scroll_delta);
+
   typedef base::hash_map<UIResourceId, UIResourceData>
       UIResourceMap;
   UIResourceMap ui_resource_map_;