Implement DelegationTracker for tracking delegated permissions to RenderFrameHosts

content/public/browser/permission_type.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_PERMISSION_TYPE_H_
 #define CONTENT_PUBLIC_BROWSER_PERMISSION_TYPE_H_
 
 namespace content {
 
 // This enum is also used for UMA purposes, so it needs to adhere to
@@ skipping 10 matching lines @@
   MIDI = 6,
   DURABLE_STORAGE = 7,
   AUDIO_CAPTURE = 8,
   VIDEO_CAPTURE = 9,
   BACKGROUND_SYNC = 10,
 
   // Always keep this at the end.
   NUM,
 };
 
+struct PermissionTypeHash {

[Charlie Reis, 2016/06/20 21:34:21]

This should stay outside content/ unless something within content/ uses it.  

See https://www.chromium.org/developers/content-module/content-api:
"all classes/structs/enums in the public API must be used by embedders and
content. i.e. if the chrome layer uses a struct but content doesn't know about
it, it doesn't belong in content/public but instead some module that's higher
level."

[raymes, 2016/06/22 03:48:11]

Done.

+  std::size_t operator()(const content::PermissionType& type) const {
+    return static_cast<size_t>(type);
+  }
+};
+
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_PERMISSION_TYPE_H_