user_manager: Remove deps on session_manager

components/user_manager/user_manager.h

Index: components/user_manager/user_manager.h
diff --git a/components/user_manager/user_manager.h b/components/user_manager/user_manager.h
index e79087351147da96469dcd3aadacc48a89f16a11..fa8b9ce7907978c94c4150909b99eff3fa5349b8 100644
--- a/components/user_manager/user_manager.h
+++ b/components/user_manager/user_manager.h
@@ -169,14 +169,8 @@ class USER_MANAGER_EXPORT UserManager {
   // restore has completed).
   virtual void SwitchToLastActiveUser() = 0;
 
-  // Called when browser session is started i.e. after
-  // browser_creator.LaunchBrowser(...) was called after user sign in.
-  // When user is at the image screen IsUserLoggedIn() will return true
-  // but IsSessionStarted() will return false. During the kiosk splash screen,
-  // we perform additional initialization after the user is logged in but
-  // before the session has been started.
-  // Fires NOTIFICATION_SESSION_STARTED.
-  virtual void SessionStarted() = 0;
+  // Invoked by session manager to inform session start.
+  virtual void OnSessionStarted() = 0;
 
   // Removes the user from the device. Note, it will verify that the given user
   // isn't the owner, so calling this method for the owner will take no effect.
@@ -301,11 +295,6 @@ class USER_MANAGER_EXPORT UserManager {
   // Returns true if we're logged in as the stub user used for testing on Linux.
   virtual bool IsLoggedInAsStub() const = 0;
 
-  // Returns true if we're logged in and browser has been started i.e.
-  // browser_creator.LaunchBrowser(...) was called after sign in
-  // or restart after crash.
-  virtual bool IsSessionStarted() const = 0;
-
   // Returns true if data stored or cached for the user with the given
   // |account_id|
   // address outside that user's cryptohome (wallpaper, avatar, OAuth token