gfx: Add FrameTime and DisplayTime classes

cc/layers/picture_layer_impl.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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 
 #include "base/time/time.h"
 #include "cc/base/math_util.h"
@@ skipping 296 matching lines @@
   if (!layer_tree_impl()->device_viewport_valid_for_tile_management()) {
     for (size_t i = 0; i < tilings_->num_tilings(); ++i)
       DCHECK(tilings_->tiling_at(i)->has_ever_been_updated());
     return;
   }
 
   if (!tilings_->num_tilings())
     return;
 
   double current_frame_time_in_seconds =
-      (layer_tree_impl()->CurrentFrameTimeTicks() -
-       base::TimeTicks()).InSecondsF();
+      layer_tree_impl()->CurrentFrameTimeTicks().Unsafe_InSecondsF();
 
   bool tiling_needs_update = false;
   for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
     if (tilings_->tiling_at(i)->NeedsUpdateForFrameAtTime(
             current_frame_time_in_seconds)) {
       tiling_needs_update = true;
       break;
     }
   }
   if (!tiling_needs_update)
@@ skipping 763 matching lines @@
   }
   state->Set("coverage_tiles", coverage_tiles.release());
   state->SetBoolean("is_using_lcd_text", is_using_lcd_text_);
 }
 
 size_t PictureLayerImpl::GPUMemoryUsageInBytes() const {
   return tilings_->GPUMemoryUsageInBytes();
 }
 
 }  // namespace cc