[Sync] Fix comment for the SyncInitialState enum.

Disabled via dashboard does not fall under CAN_START.

BUG=555113

Review URL: https://codereview.chromium.org/1519593002

Cr-Commit-Position: refs/heads/master@{#364481}

components/browser_sync/browser/profile_sync_service.h

@@ -658,10 +658,9 @@ class ProfileSyncService : public sync_driver::SyncService,
 
   // The initial state of sync, for the Sync.InitialState histogram. Even if
   // this value is CAN_START, sync startup might fail for reasons that we may
-  // want to consider logging in the future, such as sync being disabled via
-  // Google Dashboard (birthday error), a passphrase needed for decryption, or
-  // the version of Chrome being too old. This enum is used to back a UMA
-  // histogram, and should therefore be treated as append-only.
+  // want to consider logging in the future, such as a passphrase needed for
+  // decryption, or the version of Chrome being too old. This enum is used to
+  // back a UMA histogram, and should therefore be treated as append-only.
   enum SyncInitialState {
     CAN_START,                // Sync can attempt to start up.
     NOT_SIGNED_IN,            // There is no signed in user.