Add probe to warm data reduction proxy

components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc

Index: components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc b/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
index 5fc9213ec3c6fd04c11bd95f5d06726de20c929f..67b101115640cbd0779c00339a3cc44e72e75c42 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_settings.cc
@@ -304,6 +304,12 @@ DataReductionProxySettings::GetDailyReceivedContentLengths() {
 void DataReductionProxySettings::OnURLFetchComplete(
     const net::URLFetcher* source) {
   DCHECK(thread_checker_.CalledOnValidThread());
+
+  // The purpose of sending a request for the warmup URL is to warm the
+  // connection to the data_reduction_proxy. The result is ignored.
+  if (source == warmup_fetcher_.get())
+    return;
+

[marq (ping after 24h), 2014/06/16 17:23:35]

DCHECK(source == fetcher_.get()), so that adding another fetcher and not
handling it here is a programming error.

[bengr, 2014/06/17 03:42:09]

Done.

   net::URLRequestStatus status = source->GetStatus();
   if (status.status() == net::URLRequestStatus::FAILED &&
       status.error() == net::ERR_INTERNET_DISCONNECTED) {
@@ -399,6 +405,7 @@ void DataReductionProxySettings::OnIPAddressChanged() {
   if (enabled_by_user_) {
     DCHECK(params_->allowed());
     ProbeWhetherDataReductionProxyIsAvailable();
+    WarmProxyConnection();
   }
 }
 
@@ -451,8 +458,10 @@ void DataReductionProxySettings::MaybeActivateDataReductionProxy(
                   at_startup);
 
   // Check if the proxy has been restricted explicitly by the carrier.
-  if (enabled_by_user_)
+  if (enabled_by_user_) {
     ProbeWhetherDataReductionProxyIsAvailable();
+    WarmProxyConnection();
+  }
 }
 
 void DataReductionProxySettings::SetProxyConfigs(bool enabled,
@@ -581,12 +590,15 @@ base::string16 DataReductionProxySettings::AuthHashForSalt(
   return base::UTF8ToUTF16(base::MD5String(salted_key));
 }
 
-net::URLFetcher* DataReductionProxySettings::GetURLFetcher() {
-  DCHECK(url_request_context_getter_);
-  net::URLFetcher* fetcher = net::URLFetcher::Create(params_->probe_url(),
+net::URLFetcher* DataReductionProxySettings::GetBaseURLFetcher(
+    const GURL& gurl,
+    int load_flags) {
+
+  net::URLFetcher* fetcher = net::URLFetcher::Create(gurl,
                                                      net::URLFetcher::GET,
                                                      this);
-  fetcher->SetLoadFlags(net::LOAD_DISABLE_CACHE | net::LOAD_BYPASS_PROXY);
+  fetcher->SetLoadFlags(load_flags);
+  DCHECK(url_request_context_getter_);
   fetcher->SetRequestContext(url_request_context_getter_);
   // Configure max retries to be at most kMaxRetries times for 5xx errors.
   static const int kMaxRetries = 5;
@@ -595,6 +607,13 @@ net::URLFetcher* DataReductionProxySettings::GetURLFetcher() {
   return fetcher;
 }
 
+
+net::URLFetcher* DataReductionProxySettings::GetURLFetcher() {

[marq (ping after 24h), 2014/06/16 17:23:34]

I think you can tighten things up a bit and roll the specific fetcher getters
into ProbeWhetherDataReductionProxyIsAvailable() and WarmProxyConnection(), and
just use GetBaseURLFetcher as the injection point for mocks in the tests.
Because the URL gets passed into GetBaseURLFetcher(), the mocking code can
expect calls with specific inputs and return the right response for each URL.

[bengr, 2014/06/17 03:42:09]

This is the way it is to make testing easier. 

+  return GetBaseURLFetcher(params_->probe_url(),
+                           net::LOAD_DISABLE_CACHE | net::LOAD_BYPASS_PROXY);
+}
+
+
 void DataReductionProxySettings::ProbeWhetherDataReductionProxyIsAvailable() {
   net::URLFetcher* fetcher = GetURLFetcher();
   if (!fetcher)
@@ -603,4 +622,17 @@ void DataReductionProxySettings::ProbeWhetherDataReductionProxyIsAvailable() {
   fetcher_->Start();
 }
 
+net::URLFetcher* DataReductionProxySettings::GetURLFetcherForWarmup() {
+  return GetBaseURLFetcher(params_->warmup_url(),
+                           net::LOAD_DISABLE_CACHE);

[marq (ping after 24h), 2014/06/16 17:23:35]

This will fit on one line.

[bengr, 2014/06/17 03:42:09]

Done.

+}
+
+void DataReductionProxySettings::WarmProxyConnection() {
+  net::URLFetcher* fetcher = GetURLFetcherForWarmup();
+  if (!fetcher)
+    return;
+  warmup_fetcher_.reset(fetcher);
+  warmup_fetcher_->Start();
+}
+
 }  // namespace data_reduction_proxy