Remove unused variable OcclusionTracker::prevent_occlusion.

cc/trees/layer_tree_host.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/layer_tree_host.h"
 
 #include <algorithm>
 #include <stack>
 #include <string>
 
@@ skipping 1015 matching lines @@
   OcclusionTracker occlusion_tracker(
       root_layer_->render_surface()->content_rect(), record_metrics_for_frame);
   occlusion_tracker.set_minimum_tracking_size(
       settings_.minimum_occlusion_tracking_size);
 
   PrioritizeTextures(render_surface_layer_list,
                      occlusion_tracker.overdraw_metrics());
 
   in_paint_layer_contents_ = true;
 
-  const bool prevent_occlusion = false;
   LayerIteratorType end = LayerIteratorType::End(&render_surface_layer_list);
   for (LayerIteratorType it =
            LayerIteratorType::Begin(&render_surface_layer_list);
        it != end;
        ++it) {
-    occlusion_tracker.EnterLayer(it, prevent_occlusion);
+    occlusion_tracker.EnterLayer(it);
 
     if (it.represents_target_render_surface()) {
       PaintMasksForRenderSurface(
           *it, queue, did_paint_content, need_more_updates);
     } else if (it.represents_itself() && it->DrawsContent()) {
       devtools_instrumentation::ScopedLayerTreeTask
           update_layer(devtools_instrumentation::kUpdateLayer, it->id(), id());
       DCHECK(!it->paint_properties().bounds.IsEmpty());
       *did_paint_content |= it->Update(queue, &occlusion_tracker);
       *need_more_updates |= it->NeedMoreUpdates();
@@ skipping 211 matching lines @@
 
 bool LayerTreeHost::ScheduleMicroBenchmark(
     const std::string& benchmark_name,
     scoped_ptr<base::Value> value,
     const MicroBenchmark::DoneCallback& callback) {
   return micro_benchmark_controller_.ScheduleRun(
       benchmark_name, value.Pass(), callback);
 }
 
 }  // namespace cc