Treat "changes_remaining == 0" as a firm bound that indicates

the end of a batch.  The server implementation has always been consistent with this treatment.

This has the effect of eliminating a GetUpdates proximate to a commit (we do 3 total instead of 4).

BUG=55279
TEST=Integration tests + Manual testing of sync with trace breakpoints.

Review URL: http://codereview.chromium.org/3402003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@59555 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 11 insertions, 3 deletions

diff --git a/chrome/browser/sync/engine/download_updates_command.cc b/chrome/browser/sync/engine/download_updates_command.cc
index b3606fd..da88447 100644
--- a/chrome/browser/sync/engine/download_updates_command.cc
+++ b/chrome/browser/sync/engine/download_updates_command.cc
@@ -94,7 +94,9 @@ void DownloadUpdatesCommand::ExecuteImpl(SyncSession* session) {
 
   LOG(INFO) << "GetUpdates from ts " << get_updates->from_timestamp()
             << " returned " << update_response.get_updates().entries_size()
-            << " updates.";
+            << " updates and indicated "
+            << update_response.get_updates().changes_remaining()
+            << " updates left on server.";
 }
 
 void DownloadUpdatesCommand::SetRequestedTypes(
diff --git a/chrome/browser/sync/sessions/status_controller.cc b/chrome/browser/sync/sessions/status_controller.cc
index cb15468..21159d8 100644
--- a/chrome/browser/sync/sessions/status_controller.cc
+++ b/chrome/browser/sync/sessions/status_controller.cc
@@ -230,8 +230,14 @@ bool StatusController::ServerSaysNothingMoreToDownload() const {
       return false;
     }
   }
-  // The server indicates "you're up to date" by not sending a new
-  // timestamp.
+  // Changes remaining is an estimate, but if it's estimated to be
+  // zero, that's firm and we don't have to ask again.
+  if (updates_response().get_updates().has_changes_remaining() &&
+      updates_response().get_updates().changes_remaining() == 0) {
+    return true;
+  }
+  // Otherwise, the server can also indicate "you're up to date"
+  // by not sending a new timestamp.
   return !updates_response().get_updates().has_new_timestamp();
 }