Revert of cc: Add occlusion checker as a fixed view of occlusion tracker.

cc/cc.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 463 matching lines @@
         'trees/layer_tree_host.h',
         'trees/layer_tree_host_client.h',
         'trees/layer_tree_host_common.cc',
         'trees/layer_tree_host_common.h',
         'trees/layer_tree_host_impl.cc',
         'trees/layer_tree_host_impl.h',
         'trees/layer_tree_impl.cc',
         'trees/layer_tree_impl.h',
         'trees/layer_tree_settings.cc',
         'trees/layer_tree_settings.h',
-        'trees/occlusion.cc',
-        'trees/occlusion.h',
         'trees/occlusion_tracker.cc',
         'trees/occlusion_tracker.h',
         'trees/proxy.cc',
         'trees/proxy.h',
         'trees/proxy_timing_history.cc',
         'trees/proxy_timing_history.h',
         'trees/scoped_abort_remaining_swap_promises.h',
         'trees/single_thread_proxy.cc',
         'trees/single_thread_proxy.h',
         'trees/thread_proxy.cc',
@@ skipping 37 matching lines @@
         'surfaces/surface_id_allocator.h',
         'surfaces/surface_manager.cc',
         'surfaces/surface_manager.h',
         'surfaces/surface_resource_holder.cc',
         'surfaces/surface_resource_holder.h',
         'surfaces/surfaces_export.h',
       ],
     },
   ],
 }