Renamed ChannelObserver to better describe its purpose

ui/ozone/platform/drm/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.
 
 import("//build/config/linux/pkg_config.gni")
 import("//ui/ozone/ozone.gni")
 
 declare_args() {
   use_mesa_platform_null = false
   use_drm_atomic = false
@@ skipping 69 matching lines @@
     "gpu/hardware_display_plane_manager_legacy.h",
     "gpu/overlay_plane.cc",
     "gpu/overlay_plane.h",
     "gpu/page_flip_request.cc",
     "gpu/page_flip_request.h",
     "gpu/proxy_helpers.cc",
     "gpu/proxy_helpers.h",
     "gpu/scanout_buffer.h",
     "gpu/screen_manager.cc",
     "gpu/screen_manager.h",
-    "host/channel_observer.h",
     "host/drm_cursor.cc",
     "host/drm_cursor.h",
     "host/drm_cursor_core.cc",
     "host/drm_cursor_core.h",
     "host/drm_device_handle.cc",
     "host/drm_device_handle.h",
     "host/drm_display_host.cc",
     "host/drm_display_host.h",
     "host/drm_display_host_manager.cc",
     "host/drm_display_host_manager.h",
     "host/drm_display_host_manager_core.cc",
     "host/drm_display_host_manager_core.h",
     "host/drm_gpu_platform_support_host.cc",
     "host/drm_gpu_platform_support_host.h",
     "host/drm_native_display_delegate.cc",
     "host/drm_native_display_delegate.h",
     "host/drm_overlay_candidates_host.cc",
     "host/drm_overlay_candidates_host.h",
     "host/drm_overlay_manager.cc",
     "host/drm_overlay_manager.h",
     "host/drm_overlay_manager_core.cc",
     "host/drm_overlay_manager_core.h",
     "host/drm_window_host.cc",
     "host/drm_window_host.h",
     "host/drm_window_host_manager.cc",
     "host/drm_window_host_manager.h",
+    "host/gpu_thread_observer.h",
     "ozone_platform_gbm.cc",
     "ozone_platform_gbm.h",
   ]
 
   deps = [
     "//base",
     "//ipc",
     "//skia",
     "//third_party/minigbm",
     "//ui/base",
@@ skipping 62 matching lines @@
   deps = [
     ":gbm",
     "//skia",
     "//testing/gtest",
     "//ui/gfx",
     "//ui/ozone",
   ]
 
   public_configs = [ ":libdrm" ]
 }