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

cc/BUILD.gn

 # Copyright 2014 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.
 
 component("cc") {
   sources = [
     "animation/animation.cc",
     "animation/animation.h",
     "animation/animation_curve.cc",
     "animation/animation_curve.h",
@@ skipping 434 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 344 matching lines @@
     "//gpu/command_buffer/common:gles2_utils",
     "//media",
     "//skia",
     "//testing/gmock",
     "//testing/gtest",
     "//testing/perf",
     "//ui/gfx",
     "//ui/gfx/geometry",
   ]
 }