Add iOS support to ProxyService

chrome/browser/net/pref_proxy_config_tracker_impl.cc

Index: chrome/browser/net/pref_proxy_config_tracker_impl.cc
diff --git a/chrome/browser/net/pref_proxy_config_tracker_impl.cc b/chrome/browser/net/pref_proxy_config_tracker_impl.cc
index 6b4c30f35a42b13a52b695ae886cc6d716cbd3b2..47b1078533c9896bfcd3a8fb783f4bf57912b8ff 100644
--- a/chrome/browser/net/pref_proxy_config_tracker_impl.cc
+++ b/chrome/browser/net/pref_proxy_config_tracker_impl.cc
@@ -314,6 +314,10 @@ void PrefProxyConfigTrackerImpl::Observe(
 
 ProxyPrefs::ConfigState PrefProxyConfigTrackerImpl::ReadPrefConfig(
     net::ProxyConfig* config) {
+#if defined(OS_IOS)
+  return ProxyPrefs::CONFIG_UNSET;
+#else
+
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   // Clear the configuration and source.
@@ -342,4 +346,5 @@ ProxyPrefs::ConfigState PrefProxyConfigTrackerImpl::ReadPrefConfig(
   }
 
   return config_state;
+#endif  // defined(OS_IOS)
 }