Fix potential crashes in NetworkHandler code

chrome/browser/chromeos/proxy_config_service_impl.cc

 // Copyright (c) 2012 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/chromeos/proxy_config_service_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/location.h"
@@ skipping 99 matching lines @@
   VLOG_IF(1, new_network) << "New network: name=" << new_network->name()
                           << ", profile=" << new_network->profile_path();
 
   // Even if the default network is the same, its proxy config (e.g. if private
   // version of network replaces the shared version after login), or
   // use-shared-proxies setting (e.g. after login) may have changed, so
   // re-determine effective proxy config, and activate if different.
   DetermineEffectiveConfigFromDefaultNetwork();
 }
 
+void ProxyConfigServiceImpl::OnShuttingDown() {
+  // Ownership of this class is complicated. Stop observing NetworkStateHandler
+  // when the class shuts down.
+  NetworkHandler::Get()->network_state_handler()->RemoveObserver(this,
+                                                                 FROM_HERE);
+}
+
 // static
 bool ProxyConfigServiceImpl::IgnoreProxy(const PrefService* profile_prefs,
                                          const std::string network_profile_path,
                                          ::onc::ONCSource onc_source) {
   if (!profile_prefs) {
     // If the profile preference are not available, this must be the object
     // associated to local state used for system requests or login-profile. Make
     // sure that proxies are enabled.
     VLOG(1) << "Use proxy for system requests and sign-in screen.";
     return false;
@@ skipping 30 matching lines @@
     }
   }
 
   // This network is shared and not managed by the user's domain.
   bool use_shared_proxies = profile_prefs->GetBoolean(prefs::kUseSharedProxies);
   VLOG(1) << "Use proxy of shared network: " << use_shared_proxies;
   return !use_shared_proxies;
 }
 
 void ProxyConfigServiceImpl::DetermineEffectiveConfigFromDefaultNetwork() {
+  if (!NetworkHandler::IsInitialized())
+    return;
+
   NetworkStateHandler* handler = NetworkHandler::Get()->network_state_handler();
   const NetworkState* network = handler->DefaultNetwork();
 
   // Get prefs proxy config if available.
   net::ProxyConfig pref_config;
   ProxyPrefs::ConfigState pref_state = GetProxyConfig(&pref_config);
 
   // Get network proxy config if available.
   net::ProxyConfig network_config;
   net::ProxyConfigService::ConfigAvailability network_availability =
@@ skipping 52 matching lines @@
     if (VLOG_IS_ON(1) && !update_pending()) {  // Update was successful.
       scoped_ptr<base::DictionaryValue> config_dict(effective_config.ToValue());
       VLOG(1) << this << ": Proxy changed: "
               << ProxyPrefs::ConfigStateToDebugString(active_config_state_)
               << ", " << *config_dict;
     }
   }
 }
 
 }  // namespace chromeos