extensions: Use stl utilities from the base namespace

extensions/browser/app_window/app_window_geometry_cache.cc

Index: extensions/browser/app_window/app_window_geometry_cache.cc
diff --git a/extensions/browser/app_window/app_window_geometry_cache.cc b/extensions/browser/app_window/app_window_geometry_cache.cc
index e1ee46ea411b8d060e345867a73058c29c0ca7a3..b2e13ab6617833242aa2b77c9857694faf3b83c0 100644
--- a/extensions/browser/app_window/app_window_geometry_cache.cc
+++ b/extensions/browser/app_window/app_window_geometry_cache.cc
@@ -56,7 +56,7 @@ void AppWindowGeometryCache::SaveGeometry(const std::string& extension_id,
   if (extension_data[window_id].bounds == bounds &&
       extension_data[window_id].window_state == window_state &&
       extension_data[window_id].screen_bounds == screen_bounds &&
-      !ContainsKey(unsynced_extensions_, extension_id))
+      !base::ContainsKey(unsynced_extensions_, extension_id))
     return;
 
   base::Time now = base::Time::Now();