Implement Chromium side of MediaKeys.isTypeSupported().

content/content_common.gypi

 # Copyright (c) 2012 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',
     '../components/tracing.gyp:tracing',
     '../gpu/command_buffer/command_buffer.gyp:gles2_utils',
     '../net/net.gyp:net',
@@ skipping 40 matching lines @@
       'public/common/content_descriptors.h',
       'public/common/content_ipc_logging.h',
       'public/common/content_paths.h',
       'public/common/content_switches.cc',
       'public/common/content_switches.h',
       'public/common/context_menu_params.cc',
       'public/common/context_menu_params.h',
       'public/common/drop_data.cc',
       'public/common/drop_data.h',
       'public/common/eme_codec.h',
+      'public/common/eme_init_data_type.h',
       'public/common/favicon_url.cc',
       'public/common/favicon_url.h',
       'public/common/file_chooser_params.cc',
       'public/common/file_chooser_params.h',
       'public/common/frame_navigate_params.cc',
       'public/common/frame_navigate_params.h',
       'public/common/geoposition.cc',
       'public/common/geoposition.h',
       'public/common/gpu_memory_stats.cc',
       'public/common/gpu_memory_stats.h',
@@ skipping 826 matching lines @@
       ],
       'sources': [
         'common/gpu/client/gpu_memory_buffer_impl_ozone.cc',
       ],
       'sources!': [
         'common/gpu/client/gpu_memory_buffer_impl_linux.cc',
       ],
     }],
   ],
 }