[sync] Scope BrowserListRouterHelper to browsers with a matching profile

chrome/browser/sync/sessions/browser_list_router_helper.h

Index: chrome/browser/sync/sessions/browser_list_router_helper.h
diff --git a/chrome/browser/sync/sessions/browser_list_router_helper.h b/chrome/browser/sync/sessions/browser_list_router_helper.h
index 16eccdd90161bf2694b6c7adf7a985344602e202..8d9835a4520eec58f6920fbaef2b31d14b5dce24 100644
--- a/chrome/browser/sync/sessions/browser_list_router_helper.h
+++ b/chrome/browser/sync/sessions/browser_list_router_helper.h
@@ -18,10 +18,13 @@ namespace sync_sessions {
 class BrowserListRouterHelper : public chrome::BrowserListObserver,
                                 public TabStripModelObserver {
  public:
-  explicit BrowserListRouterHelper(SyncSessionsWebContentsRouter* router);
+  explicit BrowserListRouterHelper(SyncSessionsWebContentsRouter* router,
+                                   Profile* profile);
   ~BrowserListRouterHelper() override;
 
  private:
+  friend class BrowserListRouterHelperTest;
+
   // chrome::BrowserListObserver implementation.
   void OnBrowserAdded(Browser* browser) override;
   void OnBrowserRemoved(Browser* browser) override;
@@ -34,6 +37,10 @@ class BrowserListRouterHelper : public chrome::BrowserListObserver,
   // |router_| owns |this|.
   SyncSessionsWebContentsRouter* router_;
 
+  Profile* profile_;
+
+  std::set<Browser*> attached_browsers_;
+
   DISALLOW_COPY_AND_ASSIGN(BrowserListRouterHelper);
 };