Make gfx::Rect class operations consistently mutate the class they are called on.

ui/views/animation/bounds_animator.cc

 // Copyright (c) 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.
 
 #include "ui/views/animation/bounds_animator.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/base/animation/animation_container.h"
 #include "ui/base/animation/slide_animation.h"
 #include "ui/views/animation/bounds_animator_observer.h"
@@ skipping 217 matching lines @@
 
 void BoundsAnimator::AnimationProgressed(const Animation* animation) {
   DCHECK(animation_to_view_.find(animation) != animation_to_view_.end());
 
   View* view = animation_to_view_[animation];
   DCHECK(view);
   const Data& data = data_[view];
   gfx::Rect new_bounds =
       animation->CurrentValueBetween(data.start_bounds, data.target_bounds);
   if (new_bounds != view->bounds()) {
-    gfx::Rect total_bounds = new_bounds.Union(view->bounds());
+    gfx::Rect total_bounds = view->bounds();
+    total_bounds.Union(new_bounds);
 
     // Build up the region to repaint in repaint_bounds_. We'll do the repaint
     // when all animations complete (in AnimationContainerProgressed).
-    if (repaint_bounds_.IsEmpty())
-      repaint_bounds_ = total_bounds;
-    else
-      repaint_bounds_ = repaint_bounds_.Union(total_bounds);
+    repaint_bounds_.Union(total_bounds);
 
     view->SetBoundsRect(new_bounds);
   }
 
   if (data.delegate)
     data.delegate->AnimationProgressed(animation);
 }
 
 void BoundsAnimator::AnimationEnded(const Animation* animation) {
   AnimationEndedOrCanceled(animation, ANIMATION_ENDED);
@@ skipping 23 matching lines @@
     FOR_EACH_OBSERVER(BoundsAnimatorObserver,
                       observers_,
                       OnBoundsAnimatorDone(this));
   }
 }
 
 void BoundsAnimator::AnimationContainerEmpty(AnimationContainer* container) {
 }
 
 }  // namespace views