Enable using system proxy resolver for android webview.

android_webview/browser/net/aw_url_request_context_getter.cc

Index: android_webview/browser/net/aw_url_request_context_getter.cc
diff --git a/android_webview/browser/net/aw_url_request_context_getter.cc b/android_webview/browser/net/aw_url_request_context_getter.cc
index 1c74bd042000c70c070b1f2e3e60299affa8b5e0..912e3d813fdbb5779ff1fec5622124a5bbfcf2d2 100644
--- a/android_webview/browser/net/aw_url_request_context_getter.cc
+++ b/android_webview/browser/net/aw_url_request_context_getter.cc
@@ -200,14 +200,12 @@ void AwURLRequestContextGetter::InitializeURLRequestContext() {
 #if !defined(DISABLE_FTP_SUPPORT)
   builder.set_ftp_enabled(false);  // Android WebView does not support ftp yet.
 #endif
-  if (data_reduction_proxy_config_service_.get()) {
-    builder.set_proxy_config_service(
-        data_reduction_proxy_config_service_.release());
-  } else {
-    builder.set_proxy_config_service(
-        net::ProxyService::CreateSystemProxyConfigService(
-            GetNetworkTaskRunner(), NULL /* Ignored on Android */ ));
-  }
+  DCHECK(data_reduction_proxy_config_service_.get());
+  // Create proxy without a resolver since we rely on system proxy resolver.

[eroman, 2014/11/21 01:55:15]

I don't follow this comment. If no ProxyResolver is passed, then it is not
possible to use the system proxy resolver (since it is through ProxyResolver
that it would interact with either the system proxy resolver or the v8 one).

[sgurun-gerrit only, 2014/11/21 02:13:37]

Himm, there is some background to this. Android provides a local HTTP proxy that
does the proxying. This local HTTP proxy also reflects the PAC setting (if it is
set). Android proxy change intents broadcast the local host/port pair. 

I will update the comments to better explain this.

Because of this trick, PAC was actually working for Android webview in L
release.

+  builder.set_proxy_service(
+      net::ProxyService::CreateWithoutProxyResolver(
+          data_reduction_proxy_config_service_.release(),
+          net_log_.get()));
   builder.set_accept_language(net::HttpUtil::GenerateAcceptLanguageHeader(
       AwContentBrowserClient::GetAcceptLangsImpl()));
   builder.set_net_log(net_log_.get());