Revert of Enforce marking "override" for functions overriding Blink.

cc/blink/web_scroll_offset_animation_curve_impl.h

 // Copyright 2014 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.
 
 #ifndef CC_BLINK_WEB_SCROLL_OFFSET_ANIMATION_CURVE_IMPL_H_
 #define CC_BLINK_WEB_SCROLL_OFFSET_ANIMATION_CURVE_IMPL_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/blink/cc_blink_export.h"
 #include "third_party/WebKit/public/platform/WebScrollOffsetAnimationCurve.h"
@@ skipping 15 matching lines @@
   ~WebScrollOffsetAnimationCurveImpl() override;
 
   // blink::WebCompositorAnimationCurve implementation.
   AnimationCurveType type() const override;
 
   // blink::WebScrollOffsetAnimationCurve implementation.
   void setInitialValue(blink::WebFloatPoint initial_value) override;
   blink::WebFloatPoint getValue(double time) const override;
   double duration() const override;
 
-  blink::WebFloatPoint targetValue() const override;
-  void updateTarget(double time, blink::WebFloatPoint new_target) override;
+  virtual blink::WebFloatPoint targetValue() const;
+  virtual void updateTarget(double time, blink::WebFloatPoint new_target);
 
   scoped_ptr<cc::AnimationCurve> CloneToAnimationCurve() const;
 
  private:
   scoped_ptr<cc::ScrollOffsetAnimationCurve> curve_;
 
   DISALLOW_COPY_AND_ASSIGN(WebScrollOffsetAnimationCurveImpl);
 };
 
 }  // namespace cc_blink
 
 #endif  // CC_BLINK_WEB_SCROLL_OFFSET_ANIMATION_CURVE_IMPL_H_