[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/trees/damage_tracker.cc

 // Copyright 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.
 
 #include "cc/trees/damage_tracker.h"
 
 #include <algorithm>
 
 #include "cc/base/math_util.h"
 #include "cc/layers/heads_up_display_layer_impl.h"
@@ skipping 31 matching lines @@
   ExpandRectWithFilters(&filter_rect, filters);
 
   expanded_damage_rect.Intersect(filter_rect);
   damage_rect->Union(expanded_damage_rect);
 }
 
 void DamageTracker::UpdateDamageTrackingState(
     const LayerImplList& layer_list,
     int target_surface_layer_id,
     bool target_surface_property_changed_only_from_descendant,
-    gfx::Rect target_surface_content_rect,
+    const gfx::Rect& target_surface_content_rect,
     LayerImpl* target_surface_mask_layer,
     const FilterOperations& filters) {
   //
   // This function computes the "damage rect" of a target surface, and updates
   // the state that is used to correctly track damage across frames. The damage
   // rect is the region of the surface that may have changed and needs to be
   // redrawn. This can be used to scissor what is actually drawn, to save GPU
   // computation and bandwidth.
   //
   // The surface's damage rect is computed as the union of all possible changes
@@ skipping 333 matching lines @@
   // one in them. This means we need to redraw any pixels in the surface being
   // used for the blur in this layer this frame.
   if (layer->background_filters().HasFilterThatMovesPixels()) {
     ExpandDamageRectInsideRectWithFilters(target_damage_rect,
                                           surface_rect_in_target_space,
                                           layer->background_filters());
   }
 }
 
 }  // namespace cc