cc: Fix negative EstimatedParentDrawTimes

cc/trees/layer_tree_host_unittest_animation.cc

 // 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.
 
 #include "cc/trees/layer_tree_host.h"
 
 #include "cc/animation/animation_curve.h"
 #include "cc/animation/layer_animation_controller.h"
 #include "cc/animation/scroll_offset_animation_curve.h"
 #include "cc/animation/timing_function.h"
@@ skipping 1287 matching lines @@
       case 2:
         // Second frame: add an animation to the content layer. The root layer
         // animation has caused us to animate already during this frame.
         AddOpacityTransitionToLayer(content_.get(), 0.1, 5, 5, false);
         break;
     }
   }
 
   virtual void SwapBuffersOnThread(LayerTreeHostImpl* host_impl,
                                    bool result) OVERRIDE {
-    // The third frame is when both animations have started. Check that both
-    // have a valid start time.
-    if (++num_swap_buffers_ == 3) {
+    // After both animations have started, verify that they have valid
+    // start times.
+    num_swap_buffers_++;
+    AnimationRegistrar::AnimationControllerMap copy =
+        host_impl->animation_registrar()->active_animation_controllers();
+    if (copy.size() == 2u) {
       EndTest();
-      AnimationRegistrar::AnimationControllerMap copy =
-          host_impl->animation_registrar()->active_animation_controllers();
-      EXPECT_EQ(2u, copy.size());
+      EXPECT_GE(num_swap_buffers_, 3);
       for (AnimationRegistrar::AnimationControllerMap::iterator iter =
                copy.begin();
            iter != copy.end();
            ++iter) {
         int id = ((*iter).second->id());
         if (id == host_impl->RootLayer()->id()) {
           Animation* anim = (*iter).second->GetAnimation(Animation::Transform);
           EXPECT_GT((anim->start_time() - base::TimeTicks()).InSecondsF(), 0);
         } else if (id == host_impl->RootLayer()->children()[0]->id()) {
           Animation* anim = (*iter).second->GetAnimation(Animation::Opacity);
           EXPECT_GT((anim->start_time() - base::TimeTicks()).InSecondsF(), 0);
         }
       }
     }
   }
 
   virtual void AfterTest() OVERRIDE {}
 
  private:
   scoped_refptr<Layer> content_;
   int num_swap_buffers_;
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(
     LayerTreeHostAnimationTestAddAnimationAfterAnimating);
 
 }  // namespace
 }  // namespace cc