Migrate chrome/browser files to histogram_macros.h includes.

chrome/browser/extensions/external_install_manager.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/extensions/external_install_manager.h"
 
 #include <string>
 
 #include "base/logging.h"
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_macros.h"
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/external_install_error.h"
 #include "chrome/browser/profiles/profile.h"
 #include "content/public/browser/notification_details.h"
 #include "content/public/browser/notification_source.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/feature_switch.h"
@@ skipping 209 matching lines @@
   // It's a shame we have to use the notification system (instead of the
   // registry observer) for this, but the ExtensionUnloaded notification is
   // not sent out if the extension is disabled (which it is here).
   const std::string& extension_id =
       content::Details<const Extension>(details).ptr()->id();
   if (base::ContainsKey(errors_, extension_id))
     RemoveExternalInstallError(extension_id);
 }
 
 }  // namespace extensions