[Extensions] Add coarse metrics for extension function performance

extensions/browser/extension_function.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_
 #define EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_
 
 #include <stddef.h>
 
 #include <list>
 #include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/process/process.h"
 #include "base/sequenced_task_runner_helpers.h"
+#include "base/timer/elapsed_timer.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/console_message_level.h"
 #include "extensions/browser/extension_function_histogram_value.h"
 #include "extensions/browser/info_map.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/features/feature.h"
 #include "ipc/ipc_message.h"
 
 class ExtensionFunction;
 class UIThreadExtensionFunction;
@@ skipping 402 matching lines @@
   int source_tab_id_;
 
   // The type of the JavaScript context where this call originated.
   extensions::Feature::Context source_context_type_;
 
   // The process ID of the page that triggered this function call, or -1
   // if unknown.
   int source_process_id_;
 
  private:
+  base::ElapsedTimer timer_;
+
   void OnRespondingLater(ResponseValue response);
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionFunction);
 };
 
 // Extension functions that run on the UI thread. Most functions fall into
 // this category.
 class UIThreadExtensionFunction : public ExtensionFunction {
  public:
   // TODO(yzshen): We should be able to remove this interface now that we
@@ skipping 227 matching lines @@
  private:
   // If you're hitting a compile error here due to "final" - great! You're
   // doing the right thing, you just need to extend IOThreadExtensionFunction
   // instead of SyncIOExtensionFunction.
   ResponseAction Run() final;
 
   DISALLOW_COPY_AND_ASSIGN(SyncIOThreadExtensionFunction);
 };
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_FUNCTION_H_