[Sync] Add histograms for cookie jar state on Sessions commit

sync/sessions/sync_session_context.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // SyncSessionContext encapsulates the contextual information and engine
 // components specific to a SyncSession.  Unlike the SyncSession, the context
 // can be reused across several sync cycles.
 //
 // The context does not take ownership of its pointer members.  It's up to
 // the surrounding classes to ensure those members remain valid while the
@@ skipping 116 matching lines @@
   }
 
   bool cookie_jar_mismatch() const {
     return cookie_jar_mismatch_;
   }
 
   void set_cookie_jar_mismatch(bool cookie_jar_mismatch) {
     cookie_jar_mismatch_ = cookie_jar_mismatch;
   }
 
+  bool cookie_jar_empty() const {
+    return cookie_jar_empty_;
+  }
+
+  void set_cookie_jar_empty(bool empty_jar) {
+    cookie_jar_empty_ = empty_jar;
+  }
+
  private:
   // Rather than force clients to set and null-out various context members, we
   // extend our encapsulation boundary to scoped helpers that take care of this
   // once they are allocated. See definitions of these below.
   friend class TestScopedSessionEventListener;
 
   base::ObserverList<SyncEngineEventListener> listeners_;
 
   ServerConnectionManager* const connection_manager_;
   syncable::Directory* const directory_;
@@ skipping 39 matching lines @@
 
   // If true, indicates that we've been passed a command-line flag to force
   // enable the pre-commit update avoidance experiment described above.
   const bool client_enabled_pre_commit_update_avoidance_;
 
    // Whether the account(s) present in the content area's cookie jar match the
    // chrome account. If multiple accounts are present in the cookie jar, a
    // mismatch implies all of them are different from the chrome account.
   bool cookie_jar_mismatch_;
 
+  // If there's a cookie jar mismatch, whether the cookie jar was empty or not.
+  bool cookie_jar_empty_;
+
   DISALLOW_COPY_AND_ASSIGN(SyncSessionContext);
 };
 
 }  // namespace sessions
 }  // namespace syncer
 
 #endif  // SYNC_SESSIONS_SYNC_SESSION_CONTEXT_H_