permissions: handle request ids for permissions in permission manager

content/public/browser/permission_manager.h

Index: content/public/browser/permission_manager.h
diff --git a/content/public/browser/permission_manager.h b/content/public/browser/permission_manager.h
index 5a2e078718dab32004594a0166f442b26335da50..02cd23ba9e781dcf5051677787ca7167f24fcaf7 100644
--- a/content/public/browser/permission_manager.h
+++ b/content/public/browser/permission_manager.h
@@ -22,24 +22,20 @@ class CONTENT_EXPORT PermissionManager {
   virtual ~PermissionManager() = default;
 
   // Requests a permission on behalf of a frame identified by render_frame_host.
-  // The |request_id| is an identifier that can later be used if the request is
-  // cancelled (see CancelPermissionRequest).
   // When the permission request is handled, whether it failed, timed out or
   // succeeded, the |callback| will be run.
-  virtual void RequestPermission(
+  // Returns a request id which can be used to cancel the permission (see
+  // CancelPermissionRequest
+  virtual int RequestPermission(
       PermissionType permission,
       RenderFrameHost* render_frame_host,
-      int request_id,
       const GURL& requesting_origin,
       bool user_gesture,
       const base::Callback<void(PermissionStatus)>& callback) = 0;
 
-  // Cancels a previously requested permission. The given parameter must match
-  // the ones passed to the RequestPermission call.
-  virtual void CancelPermissionRequest(PermissionType permission,
-                                       RenderFrameHost* render_frame_host,
-                                       int request_id,
-                                       const GURL& requesting_origin) = 0;
+  // Cancels a previous permission request specified by |request_id|.

[mlamouri (slow - plz ping), 2015/09/15 12:36:14]

What happens if trying to cancel a permission that was already canceled?

+  virtual void CancelPermissionRequest(RenderFrameHost* render_frame_host,
+                                       int request_id) = 0;
 
   // Returns the permission status of a given requesting_origin/embedding_origin
   // tuple. This is not taking a RenderFrameHost because the call might happen