Correctly clear deprecated "proxy" pref set by data reduction proxy.

chrome/browser/net/spdyproxy/data_reduction_proxy_chrome_settings.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/net/spdyproxy/data_reduction_proxy_chrome_settings.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 12 matching lines @@
 using data_reduction_proxy::Client;
 using data_reduction_proxy::DataReductionProxyParams;
 using data_reduction_proxy::DataReductionProxySettings;
 
 // The Data Reduction Proxy has been turned into a "best effort" proxy,
 // meaning it is used only if the effective proxy configuration resolves to
 // DIRECT for a URL. It no longer can be a ProxyConfig in the proxy preference
 // hierarchy. This method removes the Data Reduction Proxy configuration from
 // prefs, if present. |proxy_pref_name| is the name of the proxy pref.
 void MigrateDataReductionProxyOffProxyPrefs(PrefService* prefs) {
-  DictionaryPrefUpdate update(prefs, prefs::kProxy);
-  base::DictionaryValue* dict = update.Get();
+  base::DictionaryValue* dict =
+      (base::DictionaryValue*) prefs->GetUserPrefValue(prefs::kProxy);
+  if (!dict)
+    return;
+
+  // Clear empty "proxy" dictionary created by a bug. See http://crbug/448172
+  if (dict->empty()) {
+    prefs->ClearPref(prefs::kProxy);
+    return;
+  }
+
   std::string mode;
   if (!dict->GetString("mode", &mode))
     return;
   if (ProxyModeToString(ProxyPrefs::MODE_FIXED_SERVERS) != mode)
     return;
   std::string proxy_server;
   if (!dict->GetString("server", &proxy_server))
     return;
   net::ProxyConfig::ProxyRules proxy_rules;
   proxy_rules.ParseFromString(proxy_server);
   if (!data_reduction_proxy::DataReductionProxyConfigurator::
           ContainsDataReductionProxy(proxy_rules)) {
     return;
   }
-  dict->SetString("mode", ProxyModeToString(ProxyPrefs::MODE_SYSTEM));
-  dict->SetString("server", "");
-  dict->SetString("bypass_list", "");
+  prefs->ClearPref(prefs::kProxy);
 }
 
 DataReductionProxyChromeSettings::DataReductionProxyChromeSettings(
     scoped_ptr<DataReductionProxyParams> params)
     : DataReductionProxySettings(params.Pass()) {
 }
 
 DataReductionProxyChromeSettings::~DataReductionProxyChromeSettings() {
 }
 
@@ skipping 43 matching lines @@
 #elif defined(OS_OPENBSD)
   return Client::CHROME_OPENBSD;
 #elif defined(OS_SOLARIS)
   return Client::CHROME_SOLARIS;
 #elif defined(OS_QNX)
   return Client::CHROME_QNX;
 #else
   return Client::UNKNOWN;
 #endif
 }