Instrument EDK sync Broker initialization

mojo/edk/system/node_controller.cc

Index: mojo/edk/system/node_controller.cc
diff --git a/mojo/edk/system/node_controller.cc b/mojo/edk/system/node_controller.cc
index 1472f03fd5a161e867f45409b6fe32b0a23e60e4..c543e5acec8fa4a7d3bf6ef882de105ca555809a 100644
--- a/mojo/edk/system/node_controller.cc
+++ b/mojo/edk/system/node_controller.cc
@@ -14,6 +14,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/process/process_handle.h"
+#include "base/timer/elapsed_timer.h"
 #include "crypto/random.h"
 #include "mojo/edk/embedder/embedder_internal.h"
 #include "mojo/edk/embedder/platform_channel_pair.h"
@@ -130,8 +131,11 @@ void NodeController::ConnectToParent(ScopedPlatformHandle platform_handle) {
 #if defined(OS_POSIX)
   // On posix, use the bootstrap channel for the broker and receive the node's
   // channel synchronously as the first message from the broker.
+  base::ElapsedTimer timer;
   broker_.reset(new Broker(std::move(platform_handle)));
   platform_handle = broker_->GetParentPlatformHandle();
+  UMA_HISTOGRAM_TIMES("Mojo.System.GetParentPlatformHandleSyncTime",
+                      timer.Elapsed());
 #endif
 
   io_task_runner_->PostTask(