cc: Do not allow gesture-scrolling 'overflow[-{x|y}]:hidden' layers.

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index 204884000cb5f3c766fc9549c65f315e141aef51..be5806462f2f38623d67d342c79fa6c17558e1e5 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -374,6 +374,11 @@ class CC_EXPORT LayerImpl : LayerAnimationValueObserver {
   void SetScrollable(bool scrollable) { scrollable_ = scrollable; }
   bool scrollable() const { return scrollable_; }
 
+  void SetUserScrollable(bool horizontal, bool vertical) {
+    user_scrollable_horizontal_ = horizontal;
+    user_scrollable_vertical_ = vertical;
+  }
+
   void ApplySentScrollDeltasFromAbortedCommit();
   void ApplyScrollDeltasSinceBeginFrame();
 
@@ -544,6 +549,8 @@ class CC_EXPORT LayerImpl : LayerAnimationValueObserver {
   bool scrollable_;
   bool should_scroll_on_main_thread_;
   bool have_wheel_event_handlers_;
+  bool user_scrollable_horizontal_;
+  bool user_scrollable_vertical_;
   Region non_fast_scrollable_region_;
   Region touch_event_handler_region_;
   SkColor background_color_;