cc: Make PictureLayerImpl use a better choice for animated raster scale.

cc/animation/animation_curve.h

 // Copyright 2012 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_ANIMATION_ANIMATION_CURVE_H_
 #define CC_ANIMATION_ANIMATION_CURVE_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/filter_operations.h"
@@ skipping 63 matching lines @@
   // returns false.
   virtual bool AnimatedBoundsForBox(const gfx::BoxF& box,
                                     gfx::BoxF* bounds) const = 0;
 
   // Returns true if this animation affects scale.
   virtual bool AffectsScale() const = 0;
 
   // Returns true if this animation is a translation.
   virtual bool IsTranslation() const = 0;
 
-  // Set |max_scale| to the maximum scale along any dimension during this
-  // animation. Returns false if the maximum scale cannot be computed.
-  virtual bool MaximumScale(float* max_scale) const = 0;
+  // Set |max_scale| to the maximum scale along any dimension at the end of
+  // intermediate animation target points (eg keyframe end points). When
+  // |forward_direction| is true, the animation curve assumes it plays from
+  // the first keyframe to the last, otherwise it assumes the opposite. Returns
+  // false if the maximum scale cannot be computed.
+  virtual bool MaximumTargetScale(bool forward_direction,
+                                  float* max_scale) const = 0;
 
   // Partial Animation implementation.
   virtual CurveType Type() const override;
 };
 
 class CC_EXPORT FilterAnimationCurve : public AnimationCurve {
  public:
   virtual ~FilterAnimationCurve() {}
 
   virtual FilterOperations GetValue(double t) const = 0;
   virtual bool HasFilterThatMovesPixels() const = 0;
 
   // Partial Animation implementation.
   virtual CurveType Type() const override;
 };
 
 }  // namespace cc
 
 #endif  // CC_ANIMATION_ANIMATION_CURVE_H_