Detect sync server communication errors

chrome/browser/sync/sessions/sync_session.h

Index: chrome/browser/sync/sessions/sync_session.h
diff --git a/chrome/browser/sync/sessions/sync_session.h b/chrome/browser/sync/sessions/sync_session.h
index abed10eac7fee2729f73822592e96fcf2acd02f9..30f3d3e2ea9b39c53a1fdacbbbb9d887b56633b3 100644
--- a/chrome/browser/sync/sessions/sync_session.h
+++ b/chrome/browser/sync/sessions/sync_session.h
@@ -112,6 +112,22 @@ class SyncSession {
   // engine again.
   bool HasMoreToSync() const;
 
+  // Returns true if there we did not detect any errors in this session.
+  //
+  // There are many errors that could prevent a sync cycle from succeeding.
+  // These include invalid local state, inability to contact the server,
+  // inability to authenticate with the server, and server errors.  What they
+  // have in common is that the we either need to take some action and then
+  // retry the sync cycle or, in the case of transient errors, retry after some
+  // backoff timer has expired.  Most importantly, the SyncScheduler should not
+  // assume that the original action that triggered the sync cycle (ie. a nudge
+  // or a notification) has been properly serviced.
+  //
+  // This function also returns false if SyncShare has not been called on this
+  // session yet, or if ResetTransientState() has been called on this session
+  // since the last call to SyncShare.
+  bool Succeeded() const;
+
   // Collects all state pertaining to how and why |s| originated and unions it
   // with corresponding state in |this|, leaving |s| unchanged.  Allows |this|
   // to take on the responsibilities |s| had (e.g. certain data types) in the