Only log the job controller count when it's hitting boundaries for the first time

net/http/http_stream_factory_impl.h

Index: net/http/http_stream_factory_impl.h
diff --git a/net/http/http_stream_factory_impl.h b/net/http/http_stream_factory_impl.h
index 503764c42550d4e52722ad48734b5eabc7c5dcdd..53f45368368666add65730aaee1e23841f13a320 100644
--- a/net/http/http_stream_factory_impl.h
+++ b/net/http/http_stream_factory_impl.h
@@ -174,7 +174,7 @@ class NET_EXPORT_PRIVATE HttpStreamFactoryImpl : public HttpStreamFactory {
   // Adds the count of JobControllers that are not completed to UMA histogram if
   // the count is a multiple of 100: 100, 200, 400, etc. Break down
   // JobControllers count based on the type of JobController.
-  void AddJobControllerCountToHistograms() const;
+  void AddJobControllerCountToHistograms();
 
   HttpNetworkSession* const session_;
 
@@ -196,6 +196,9 @@ class NET_EXPORT_PRIVATE HttpStreamFactoryImpl : public HttpStreamFactory {
 
   const bool for_websockets_;
 
+  // The count of JobControllers that was most recently logged to histograms.
+  size_t last_logged_job_controller_count_;
+
   DISALLOW_COPY_AND_ASSIGN(HttpStreamFactoryImpl);
 };