Introduce browser_sync::ExtensionsActivityMonitor to collect extensions API u...

chrome/browser/sync/engine/syncer.h

Index: chrome/browser/sync/engine/syncer.h
===================================================================
--- chrome/browser/sync/engine/syncer.h	(revision 30121)
+++ chrome/browser/sync/engine/syncer.h	(working copy)
@@ -19,6 +19,7 @@
 #include "chrome/browser/sync/syncable/directory_event.h"
 #include "chrome/browser/sync/util/event_sys-inl.h"
 #include "chrome/browser/sync/util/event_sys.h"
+#include "chrome/browser/sync/util/extensions_activity_monitor.h"
 #include "testing/gtest/include/gtest/gtest_prod.h"  // For FRIEND_TEST
 
 namespace syncable {
@@ -180,6 +181,10 @@
   // by the SyncerThread that created us.
   ModelSafeWorker* model_safe_worker_;
 
+  // We use this to stuff extensions activity into CommitMessages so the server
+  // can correlate commit traffic with extension-related bookmark mutations.
+  ExtensionsActivityMonitor* extensions_monitor_;
+
   // The source of the last nudge.
   sync_pb::GetUpdatesCallerInfo::GET_UPDATES_SOURCE updates_source_;