*DRAFT* Move MediaDeviceIDSalt from chrome/ to components/ and use it in Android WebView.

components/media_device_id_salt.gypi

 # Copyright 2015 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.
 
 {
   'targets': [
     {
-      # GN version: //components/profile_metrics
-      'target_name': 'profile_metrics',
+      'target_name': 'media_device_id_salt',
       'type': 'static_library',
+      'dependencies': [
+        '../base/base.gyp:base',
+        'pref_registry',
+        'prefs/prefs.gyp:prefs',
+      ],
       'include_dirs': [
         '..',
       ],
-      'dependencies': [
-        '../base/base.gyp:base',
-      ],
       'sources': [
-        # Note: sources list duplicated in GN build.
-        'profile_metrics/counts.cc',
-        'profile_metrics/counts.h',
+        'media_device_id_salt/media_device_id_salt.h',
+        'media_device_id_salt/media_device_id_salt.cc',
       ],
     },
   ],
 }