Replace WebAudio MediaCodec usage with FFmpeg. A ~4x improvement.

content/content_renderer.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',
     '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
     '../cc/cc.gyp:cc',
     '../cc/cc.gyp:cc_proto',
@@ skipping 243 matching lines @@
       'renderer/java/gin_java_function_invocation_helper.cc',
       'renderer/java/gin_java_function_invocation_helper.h',
       'renderer/manifest/manifest_manager.cc',
       'renderer/manifest/manifest_manager.h',
       'renderer/manifest/manifest_parser.cc',
       'renderer/manifest/manifest_parser.h',
       'renderer/manifest/manifest_uma_util.cc',
       'renderer/manifest/manifest_uma_util.h',
       'renderer/media/aec_dump_message_filter.cc',
       'renderer/media/aec_dump_message_filter.h',
-      'renderer/media/android/audio_decoder_android.cc',
-      'renderer/media/android/audio_decoder_android.h',
       'renderer/media/android/media_info_loader.cc',
       'renderer/media/android/media_info_loader.h',
       'renderer/media/android/media_source_delegate.cc',
       'renderer/media/android/media_source_delegate.h',
       'renderer/media/android/renderer_demuxer_android.cc',
       'renderer/media/android/renderer_demuxer_android.h',
       'renderer/media/android/renderer_media_player_manager.cc',
       'renderer/media/android/renderer_media_player_manager.h',
       'renderer/media/android/renderer_media_session_manager.cc',
       'renderer/media/android/renderer_media_session_manager.h',
@@ skipping 528 matching lines @@
         'renderer/webscrollbarbehavior_impl_mac.h',
         'renderer/webscrollbarbehavior_impl_mac.mm',
       ],
     }],
     ['OS=="win" and win_use_allocator_shim==1', {
       'dependencies': [
           '../base/allocator/allocator.gyp:allocator',
       ],
     }],
     ['OS=="android"', {
-      'sources!': [
-        'renderer/media/audio_decoder.cc',
-      ],
       'sources': [
         'renderer/external_popup_menu.cc',
         'renderer/external_popup_menu.h',
       ],
       'dependencies': [
         '../build/android/ndk.gyp:cpu_features',
         '../third_party/libphonenumber/libphonenumber.gyp:libphonenumber',
       ],
       'dependencies!': [
         '../device/battery/battery.gyp:device_battery',
@@ skipping 99 matching lines @@
     }],
   ],
   'target_conditions': [
     ['OS=="android"', {
       'sources/': [
         ['include', '^renderer/render_view_linux\\.cc$'],
       ],
     }],
   ],
 }