Cleanup: Remove unneeded forward declarations from various chrome/browser subdirectories.

chrome/browser/metrics/metrics_log.h

Index: chrome/browser/metrics/metrics_log.h
===================================================================
--- chrome/browser/metrics/metrics_log.h	(revision 109953)
+++ chrome/browser/metrics/metrics_log.h	(working copy)
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
@@ -9,11 +9,13 @@
 #define CHROME_BROWSER_METRICS_METRICS_LOG_H_
 #pragma once
 
+#include <string>
+#include <vector>
+
 #include "base/basictypes.h"
 #include "chrome/common/metrics_helpers.h"
 
 struct AutocompleteLog;
-class GURL;
 class PrefService;
 
 namespace base {