Added interstitial page for merge session.

chrome/browser/chromeos/login/user_manager.h

Index: chrome/browser/chromeos/login/user_manager.h
diff --git a/chrome/browser/chromeos/login/user_manager.h b/chrome/browser/chromeos/login/user_manager.h
index 13a95dd2f24c8b6b94c596ad17b35f3b55a7d0fb..168ea81543dfb609f0f2cc683184573b1217b823 100644
--- a/chrome/browser/chromeos/login/user_manager.h
+++ b/chrome/browser/chromeos/login/user_manager.h
@@ -21,13 +21,27 @@ class UserImageManager;
 // who have logged into this Chrome OS device before and updating that list.
 class UserManager {
  public:
+  // Status of merge sessions process which is responsible for exchanging
+  // user OAuth2 refresh token for GAIA cookies.
+  enum MergeSessionState {
+    // Session merge hasn't started yet.
+    MERGE_STATUS_NOT_STARTED,
+    // Session merge is in process.
+    MERGE_STATUS_IN_PROCESS,
+    // Session merge is completed.
+    MERGE_STATUS_DONE,
+  };
+
   // Interface that observers of UserManager must implement in order
   // to receive notification when local state preferences is changed
   class Observer {
    public:
-    // Called when the local state preferences is changed
+    // Called when the local state preferences is changed.
     virtual void LocalStateChanged(UserManager* user_manager) = 0;
 
+    // Called when merge session state is changed.
+    virtual void MergeSessionStateChanged(MergeSessionState state) {}
+
    protected:
     virtual ~Observer() {}
   };
@@ -211,6 +225,12 @@ class UserManager {
   // or restart after crash.
   virtual bool IsSessionStarted() const = 0;
 
+  // Returns merge session status.
+  virtual MergeSessionState GetMergeSessionState() const = 0;
+
+  // Changes merge session status.
+  virtual void SetMergeSessionState(MergeSessionState status) = 0;
+
   // Returns true when the browser has crashed and restarted during the current
   // user's session.
   virtual bool HasBrowserRestarted() const = 0;