ChromeOS cryptohome should be able to use gaia id as user identifier.

chromeos/dbus/session_manager_client.h

Index: chromeos/dbus/session_manager_client.h
diff --git a/chromeos/dbus/session_manager_client.h b/chromeos/dbus/session_manager_client.h
index 4fd4c0955ea287154ff95d2e8f4a68f2b7042058..e202db91e711087790ee9ce68b1f87aec77520d1 100644
--- a/chromeos/dbus/session_manager_client.h
+++ b/chromeos/dbus/session_manager_client.h
@@ -78,7 +78,7 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
   virtual void RestartJob(const std::vector<std::string>& argv) = 0;
 
   // Starts the session for the user.
-  virtual void StartSession(const std::string& user_email) = 0;
+  virtual void StartSession(const std::string& user_id) = 0;
 
   // Stops the current session.
   virtual void StopSession() = 0;
@@ -102,7 +102,7 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
   virtual void NotifySupervisedUserCreationFinished() = 0;
 
   // Map that is used to describe the set of active user sessions where |key|
-  // is user_id and |value| is user_id_hash.
+  // is cryptohome id and |value| is user_id_hash.
   typedef std::map<std::string, std::string> ActiveSessionsMap;
 
   // The ActiveSessionsCallback is used for the RetrieveActiveSessions()
@@ -131,10 +131,10 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
   virtual void RetrieveDevicePolicy(const RetrievePolicyCallback& callback) = 0;
 
   // Fetches the user policy blob stored by the session manager for the given
-  // |username|. Upon completion of the retrieve attempt, we will call the
+  // |user_id|. Upon completion of the retrieve attempt, we will call the
   // provided callback.
   virtual void RetrievePolicyForUser(
-      const std::string& username,
+      const std::string& user_id,
       const RetrievePolicyCallback& callback) = 0;
 
   // Same as RetrievePolicyForUser() but blocks until a reply is received, and
@@ -144,7 +144,7 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
   // considered acceptable (e.g. restarting the browser after a crash or after
   // a flag change).
   virtual std::string BlockingRetrievePolicyForUser(
-      const std::string& username) = 0;
+      const std::string& user_id) = 0;
 
   // Fetches the policy blob associated with the specified device-local account
   // from session manager.  |callback| is invoked up on completion.
@@ -163,8 +163,8 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
                                  const StorePolicyCallback& callback) = 0;
 
   // Attempts to asynchronously store |policy_blob| as user policy for the given
-  // |username|. Upon completion of the store attempt, we will call callback.
-  virtual void StorePolicyForUser(const std::string& username,
+  // |user_id|. Upon completion of the store attempt, we will call callback.
+  virtual void StorePolicyForUser(const std::string& user_id,
                                   const std::string& policy_blob,
                                   const StorePolicyCallback& callback) = 0;
 
@@ -177,7 +177,7 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
 
   // Sets the flags to be applied next time by the session manager when Chrome
   // is restarted inside an already started session for a particular user.
-  virtual void SetFlagsForUser(const std::string& username,
+  virtual void SetFlagsForUser(const std::string& user_id,
                                const std::vector<std::string>& flags) = 0;
 
   typedef base::Callback<void(const std::vector<std::string>& state_keys)>