Implement progress bar spec (determinate and indeterminate).

ui/gfx/animation/linear_animation.h

 // Copyright (c) 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.
 
 #ifndef UI_GFX_ANIMATION_LINEAR_ANIMATION_H_
 #define UI_GFX_ANIMATION_LINEAR_ANIMATION_H_
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "ui/gfx/animation/animation.h"
 
 namespace gfx {
 
 class AnimationDelegate;
 
 // Linear time bounded animation. As the animation progresses AnimateToState is
 // invoked.
 class GFX_EXPORT LinearAnimation : public Animation {
  public:
   // Initializes everything except the duration.
   //
   // Caller must make sure to call SetDuration() if they use this
   // constructor; it is preferable to use the full one, but sometimes
   // duration can change between calls to Start() and we need to
   // expose this interface.
   LinearAnimation(int frame_rate, AnimationDelegate* delegate);
+  // As above, but uses a default frame rate.
+  explicit LinearAnimation(AnimationDelegate* delegate);

[sky, 2016/09/13 02:30:08]

How about the following as the only constructor:

explicit LinearAnimation(AnimationDelegate* delegate,
frame_default = kDefaultFrameFrame);
?

[Evan Stade, 2016/09/13 15:45:39]

Done.

 
   // Initializes all fields.
   LinearAnimation(int duration, int frame_rate, AnimationDelegate* delegate);
 
   // Gets the value for the current state, according to the animation curve in
   // use. This class provides only for a linear relationship, however subclasses
   // can override this to provide others.
   double GetCurrentValue() const override;
 
   // Change the current state of the animation to |new_value|.
@@ skipping 34 matching lines @@
   // If true, we're in end. This is used to determine if the animation should
   // be advanced to the end from AnimationStopped.
   bool in_end_;
 
   DISALLOW_COPY_AND_ASSIGN(LinearAnimation);
 };
 
 }  // namespace gfx
 
 #endif  // APP_LINEAR_ANIMATION_H_