cc: Disallow scroll offset animations when impl-scrolling isn't supported

cc/animation/animation_registrar.h

Index: cc/animation/animation_registrar.h
diff --git a/cc/animation/animation_registrar.h b/cc/animation/animation_registrar.h
index 579b11f8202da6e4f44c011c4d2c0cc32154932e..36c45c789049afec27223731ef745b8c962ba23a 100644
--- a/cc/animation/animation_registrar.h
+++ b/cc/animation/animation_registrar.h
@@ -51,12 +51,20 @@ class CC_EXPORT AnimationRegistrar {
     return all_animation_controllers_;
   }
 
+  void set_supports_scroll_animations(bool supports_scroll_animations) {
+    supports_scroll_animations_ = supports_scroll_animations;
+  }
+
+  bool supports_scroll_animations() { return supports_scroll_animations_; }
+
  private:
   AnimationRegistrar();
 
   AnimationControllerMap active_animation_controllers_;
   AnimationControllerMap all_animation_controllers_;
 
+  bool supports_scroll_animations_;
+
   DISALLOW_COPY_AND_ASSIGN(AnimationRegistrar);
 };