Quota: Factor out (Mock)QuotaManagerProxy into its own file for readability

webkit/browser/quota/quota_manager_unittest.cc

Index: webkit/browser/quota/quota_manager_unittest.cc
diff --git a/webkit/browser/quota/quota_manager_unittest.cc b/webkit/browser/quota/quota_manager_unittest.cc
index b5a8bdce99888075ab44cbd47761439c52aa5d31..921053784e6eb7a79155eef9c5eeedebb2ad3ced 100644
--- a/webkit/browser/quota/quota_manager_unittest.cc
+++ b/webkit/browser/quota/quota_manager_unittest.cc
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <algorithm>
 #include <set>
 #include <sstream>
 #include <vector>
@@ -22,6 +23,7 @@
 #include "webkit/browser/quota/mock_storage_client.h"
 #include "webkit/browser/quota/quota_database.h"
 #include "webkit/browser/quota/quota_manager.h"
+#include "webkit/browser/quota/quota_manager_proxy.h"
 
 using base::MessageLoopProxy;