Rewrite clipboard write IPC handling to be easier to understand.

chrome/chrome_tests.gypi

 # Copyright 2013 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': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',   
       'browser/extensions/browsertest_util.cc',
@@ skipping 839 matching lines @@
         '../ui/web_dialogs/web_dialogs.gyp:web_dialogs_test_support',
       ],
       'include_dirs': [
         '..',
       ],
       'defines': [
         'HAS_OUT_OF_PROC_TEST_RUNNER',
       ],
       'sources': [
         '../chrome/browser/ui/webui/options/language_options_interactive_uitest.cc',
+        '../content/browser/renderer_host/clipboard_message_filter_unittest.cc',
         '../extensions/browser/app_window/app_window_interactive_uitest.cc',
         '../ui/base/clipboard/clipboard_unittest.cc',
         '../ui/views/controls/webview/webview_interactive_uitest.cc',
         '../ui/views/corewm/desktop_capture_controller_unittest.cc',
         '../ui/views/widget/desktop_aura/desktop_window_tree_host_x11_interactive_uitest.cc',
         '../ui/views/widget/desktop_aura/x11_topmost_window_finder_interactive_uitest.cc',
         '../ui/views/widget/widget_interactive_uitest.cc',
         'browser/apps/app_browsertest_util.cc',
         'browser/apps/app_browsertest_util.h',
         'browser/apps/app_pointer_lock_interactive_uitest.cc',
@@ skipping 2248 matching lines @@
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }