Make Clipboard::FormatType an opaque handle type.

content/content_common.gypi

 # Copyright (c) 2011 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.
 
 {
   'dependencies': [
     '../base/base.gyp:base',
     '../build/temp_gyp/googleurl.gyp:googleurl',
     '../gpu/gpu.gyp:gpu_ipc',
     '../ipc/ipc.gyp:ipc',
@@ skipping 76 matching lines @@
     'common/child_process_host_impl.cc',
     'common/child_process_host_impl.h',
     'common/child_process_messages.h',
     'common/child_process_sandbox_support_impl_linux.cc',
     'common/child_process_sandbox_support_impl_linux.h',
     'common/child_thread.cc',
     'common/child_thread.h',
     'common/child_trace_message_filter.cc',
     'common/child_trace_message_filter.h',
     'common/chrome_descriptors.h',
+    'common/clipboard_messages.cc',
     'common/clipboard_messages.h',
     'common/content_message_generator.cc',
     'common/content_message_generator.h',
     'common/content_export.h',
     'common/content_counters.cc',
     'common/content_counters.h',
     'common/content_paths.cc',
     'common/css_colors.h',
     'common/database_messages.h',
     'common/database_util.cc',
@@ skipping 235 matching lines @@
         '../build/extract_from_cab.py',
         '..\\third_party\\directxsdk\\files\\Redist\\<(input)',
         '<(output)',
         '<(PRODUCT_DIR)',
         ],
       },
      ]
     }]
   ],
 }