[GCM] Adding GCMAccountMapper to link signed in profile to accounts.

components/gcm_driver/gcm_client.h

Index: components/gcm_driver/gcm_client.h
diff --git a/components/gcm_driver/gcm_client.h b/components/gcm_driver/gcm_client.h
index 8a7f7b21747892932828090f27f3821ad40bc44d..da6e070a89b748c0eedab833b55749cbb76d4027 100644
--- a/components/gcm_driver/gcm_client.h
+++ b/components/gcm_driver/gcm_client.h
@@ -141,6 +141,14 @@ class GCMClient {
     RecordedActivities recorded_activities;
   };
 
+  // Information about account and access token for that account.
+  // That information can be used for checkin or account mapping.
+  struct AccountTokenInfo {
+    std::string account_id;
+    std::string email;
+    std::string access_token;
+  };
+
   // A delegate interface that allows the GCMClient instance to interact with
   // its caller, i.e. notifying asynchronous event.
   class Delegate {