Revert 132455 - Abort sync cycles when download step fails

sync/engine/syncer.cc

Index: sync/engine/syncer.cc
===================================================================
--- sync/engine/syncer.cc	(revision 132475)
+++ sync/engine/syncer.cc	(working copy)
@@ -110,6 +110,17 @@
 
     switch (current_step) {
       case SYNCER_BEGIN:
+        // This isn't perfect, as we can end up bundling extensions activity
+        // intended for the next session into the current one.  We could do a
+        // test-and-reset as with the source, but note that also falls short if
+        // the commit request fails (e.g. due to lost connection), as we will
+        // fall all the way back to the syncer thread main loop in that case,
+        // creating a new session when a connection is established, losing the
+        // records set here on the original attempt.  This should provide us
+        // with the right data "most of the time", and we're only using this
+        // for analysis purposes, so Law of Large Numbers FTW.
+        session->context()->extensions_monitor()->GetAndClearRecords(
+            session->mutable_extensions_activity());
         session->context()->PruneUnthrottledTypes(base::TimeTicks::Now());
         session->SendEventNotification(SyncEngineEvent::SYNC_CYCLE_BEGIN);
 
@@ -155,19 +166,13 @@
       case STORE_TIMESTAMPS: {
         StoreTimestampsCommand store_timestamps;
         store_timestamps.Execute(session);
-        // We download all of the updates before attempting to apply them.
-        if (!session->status_controller().download_updates_succeeded()) {
-          // We may have downloaded some updates, but if the latest download
-          // attempt failed then we don't have all the updates.  We'll leave
-          // it to a retry job to pick up where we left off.
-          last_step = SYNCER_END; // Necessary for CONFIGURATION mode.
-          next_step = SYNCER_END;
-          DVLOG(1) << "Aborting sync cycle due to download updates failure";
-        } else if (!session->status_controller()
-                       .ServerSaysNothingMoreToDownload()) {
-          next_step = DOWNLOAD_UPDATES;
-        } else {
+        // We should download all of the updates before attempting to process
+        // them.
+        if (session->status_controller().ServerSaysNothingMoreToDownload() ||
+            !session->status_controller().download_updates_succeeded()) {
           next_step = APPLY_UPDATES;
+        } else {
+          next_step = DOWNLOAD_UPDATES;
         }
         break;
       }
@@ -198,19 +203,6 @@
 
         if (!session->status_controller().commit_ids().empty()) {
           DVLOG(1) << "Building a commit message";
-
-          // This isn't perfect, since the set of extensions activity may not
-          // correlate exactly with the items being committed.  That's OK as
-          // long as we're looking for a rough estimate of extensions activity,
-          // not an precise mapping of which commits were triggered by which
-          // extension.
-          //
-          // We will push this list of extensions activity back into the
-          // ExtensionsActivityMonitor if this commit turns out to not contain
-          // any bookmarks, or if the commit fails.
-          session->context()->extensions_monitor()->GetAndClearRecords(
-              session->mutable_extensions_activity());
-
           BuildCommitCommand build_commit_command;
           build_commit_command.Execute(session);