This CL replaces e-mail with AccountId in easy signin code.

components/proximity_auth/proximity_auth_system.h

Index: components/proximity_auth/proximity_auth_system.h
diff --git a/components/proximity_auth/proximity_auth_system.h b/components/proximity_auth/proximity_auth_system.h
index 4452265d9bc736f308e551413d92c414083b35bd..41316afcd5393a14d8319eda720738dd3791e1ac 100644
--- a/components/proximity_auth/proximity_auth_system.h
+++ b/components/proximity_auth/proximity_auth_system.h
@@ -14,6 +14,8 @@
 #include "components/proximity_auth/remote_device_life_cycle.h"
 #include "components/proximity_auth/screenlock_bridge.h"
 
+class AccountId;
+
 namespace proximity_auth {
 
 class ProximityAuthClient;
@@ -38,7 +40,7 @@ class ProximityAuthSystem : public RemoteDeviceLifeCycle::Observer,
   void Start();
 
   // Called when the user clicks the user pod and attempts to unlock/sign-in.
-  void OnAuthAttempted(const std::string& user_id);
+  void OnAuthAttempted(const AccountId& account_id);
 
   // Called when the system suspends.
   void OnSuspend();
@@ -56,7 +58,7 @@ class ProximityAuthSystem : public RemoteDeviceLifeCycle::Observer,
       ScreenlockBridge::LockHandler::ScreenType screen_type) override;
   void OnScreenDidUnlock(
       ScreenlockBridge::LockHandler::ScreenType screen_type) override;
-  void OnFocusedUserChanged(const std::string& user_id) override;
+  void OnFocusedUserChanged(const AccountId& account_id) override;
 
   // Resumes |remote_device_life_cycle_| after device wakes up and waits a
   // timeout.