Fix Up SingletonHwnd Observer Lifetime Issues

ui/gfx/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/ui.gni")
 import("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 204 matching lines @@
     "vsync_provider.h",
     "win/direct_write.cc",
     "win/direct_write.h",
     "win/dpi.cc",
     "win/dpi.h",
     "win/hwnd_util.cc",
     "win/hwnd_util.h",
     "win/scoped_set_map_mode.h",
     "win/singleton_hwnd.cc",
     "win/singleton_hwnd.h",
+    "win/singleton_hwnd_observer.cc",
+    "win/singleton_hwnd_observer.h",
     "win/window_impl.cc",
     "win/window_impl.h",
   ]
 
   # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   defines = [ "GFX_IMPLEMENTATION" ]
 
   deps = [
@@ skipping 293 matching lines @@
 if (is_android) {
   generate_jni("gfx_jni_headers") {
     sources = [
       "../android/java/src/org/chromium/ui/gfx/BitmapHelper.java",
       "../android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java",
       "../android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java",
     ]
     jni_package = "gfx"
   }
 }