Fix main thread top controls scrolling to mirror CC.

cc/trees/layer_tree_host_impl.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 <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 105 matching lines @@
 
     inner_->ClampScrollToMaxScrollOffset();
     outer_->ClampScrollToMaxScrollOffset();
 
     gfx::ScrollOffset viewport_location =
         inner_->CurrentScrollOffset() + outer_->CurrentScrollOffset();
 
     gfx::Vector2dF delta =
         viewport_in_content_coordinates_.DeltaFrom(viewport_location);
 
-    delta = outer_->ScrollBy(delta);
-    inner_->ScrollBy(delta);
+    delta = inner_->ScrollBy(delta);
+    outer_->ScrollBy(delta);
   }
 
  private:
   LayerImpl* inner_;
   LayerImpl* outer_;
   gfx::ScrollOffset viewport_in_content_coordinates_;
 };
 
 void DidVisibilityChange(LayerTreeHostImpl* id, bool visible) {
   if (visible) {
@@ skipping 3805 matching lines @@
   return task_runner_provider_->HasImplThread();
 }
 
 bool LayerTreeHostImpl::CommitToActiveTree() const {
   // In single threaded mode we skip the pending tree and commit directly to the
   // active tree.
   return !task_runner_provider_->HasImplThread();
 }
 
 }  // namespace cc