Make MediaSession per frame as an attribute of Navigator

third_party/WebKit/Source/modules/modules_idl_files.gni

 # Copyright 2016 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("//third_party/WebKit/Source/bindings/bindings.gni")
 
 # The paths in this file are absolute since this file is imported and the
 # file lists must be valid from multple "current directories".
 
 bindings_modules_output_dir = "$bindings_output_dir/modules"
@@ skipping 528 matching lines @@
           "filesystem/HTMLInputElementFileSystem.idl",
           "filesystem/SharedWorkerGlobalScopeFileSystem.idl",
           "filesystem/WindowFileSystem.idl",
           "gamepad/NavigatorGamepad.idl",
           "geolocation/NavigatorGeolocation.idl",
           "indexeddb/WindowIndexedDatabase.idl",
           "indexeddb/WorkerGlobalScopeIndexedDatabase.idl",
           "installedapp/NavigatorInstalledApp.idl",
           "mediacapturefromelement/HTMLCanvasElementCapture.idl",
           "mediacapturefromelement/HTMLMediaElementCapture.idl",
+          "mediasession/NavigatorMediaSession.idl",
           "mediasource/AudioTrackSourceBuffer.idl",
           "mediasource/VideoTrackSourceBuffer.idl",
           "mediasource/HTMLVideoElementMediaSource.idl",
           "mediasource/URLMediaSource.idl",
           "mediastream/NavigatorMediaStream.idl",
           "mediastream/NavigatorUserMedia.idl",
           "mediastream/URLMediaStream.idl",
           "mediastream/WindowMediaStream.idl",
           "navigatorcontentutils/NavigatorContentUtils.idl",
           "nfc/NavigatorNFC.idl",
@@ skipping 310 matching lines @@
   "$blink_modules_output_dir/websockets/CloseEventInit.h",
   "$blink_modules_output_dir/webusb/USBConnectionEventInit.cpp",
   "$blink_modules_output_dir/webusb/USBConnectionEventInit.h",
   "$blink_modules_output_dir/webusb/USBControlTransferParameters.cpp",
   "$blink_modules_output_dir/webusb/USBControlTransferParameters.h",
   "$blink_modules_output_dir/webusb/USBDeviceFilter.cpp",
   "$blink_modules_output_dir/webusb/USBDeviceFilter.h",
   "$blink_modules_output_dir/webusb/USBDeviceRequestOptions.cpp",
   "$blink_modules_output_dir/webusb/USBDeviceRequestOptions.h",
 ]