[sync] Prevent sessions flare on startup

chrome/browser/sync/sessions/sync_sessions_web_contents_router.cc

Index: chrome/browser/sync/sessions/sync_sessions_web_contents_router.cc
diff --git a/chrome/browser/sync/sessions/sync_sessions_web_contents_router.cc b/chrome/browser/sync/sessions/sync_sessions_web_contents_router.cc
index cc5ecea9384ddd638c5c96be25352ec1b5bd32e4..e682c0493d7f48ef8605057e76c78bd6185a049d 100644
--- a/chrome/browser/sync/sessions/sync_sessions_web_contents_router.cc
+++ b/chrome/browser/sync/sessions/sync_sessions_web_contents_router.cc
@@ -14,6 +14,7 @@
 #include "chrome/browser/ui/sync/tab_contents_synced_tab_delegate.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "components/history/core/browser/history_service.h"
+#include "components/sync_sessions/sync_sessions_client.h"
 #include "components/sync_sessions/synced_tab_delegate.h"
 
 namespace sync_sessions {
@@ -56,13 +57,16 @@ void SyncSessionsWebContentsRouter::NotifyTabModified(
   if (handler_ && web_contents) {
     SyncedTabDelegate* delegate =
         GetSyncedTabDelegateFromWebContents(web_contents);
-    if (delegate)
+    if (delegate) {
       handler_->OnLocalTabModified(delegate);
-  }
-
-  if (!flare_.is_null()) {
-    flare_.Run(syncer::SESSIONS);
-    flare_.Reset();
+      if (sessions_client_ && !delegate->ShouldSync(sessions_client_))
+        return;

[skym, 2017/04/18 15:50:51]

This early return feels really oddly structured.

[Patrick Noland, 2017/04/18 22:37:41]

Done.

+    }
+
+    if (!flare_.is_null()) {

[skym, 2017/04/18 15:50:51]

This looks broken to me. My understanding is that we're given the |handler_| at
the end of SessionsSyncManager::MergeDataAndStartSyncing. If your flare call is
inside if (handler_) it will never execute when it's actually needed.

[Patrick Noland, 2017/04/18 22:37:41]

Done.

+      flare_.Run(syncer::SESSIONS);
+      flare_.Reset();
+    }
   }
 }