Add probe to warm data reduction proxy

On startup and on network changes, a request is made to the data reduction proxy to warm the connection. This reduces the page load time for first loads.

BUG=354438

Review URL: https://codereview.chromium.org/338723002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@278210 0039d316-1c4b-4281-b951-d872f2087c98

12 files changed, 197 insertions, 33 deletions

diff --git a/build/common.gypi b/build/common.gypi
index 5b15e70..6d356ef 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -562,6 +562,7 @@
       'spdy_proxy_auth_property%' : '',
       'spdy_proxy_auth_value%' : '',
       'data_reduction_proxy_probe_url%' : '',
+      'data_reduction_proxy_warmup_url%' : '',
       'data_reduction_proxy_ssl_origin%' : '',
       'data_reduction_proxy_alt_origin%' : '',
       'data_reduction_proxy_alt_fallback_origin%' : '',
@@ -925,12 +926,14 @@
           'icu_use_data_file_flag%' : 1,
           'spdy_proxy_auth_origin%': '',
           'data_reduction_proxy_probe_url%': '',
+          'data_reduction_proxy_warmup_url%': '',
           'data_reduction_dev_host%': '',
           'data_reduction_fallback_host%': '',
         }, {
           'icu_use_data_file_flag%' : 0,
           'spdy_proxy_auth_origin%': 'https://proxy.googlezip.net:443/',
           'data_reduction_proxy_probe_url%': 'http://check.googlezip.net/connect',
+          'data_reduction_proxy_warmup_url%': 'http://www.gstatic.com/generate_204',
           'data_reduction_dev_host%': 'http://proxy-dev.googlezip.net:80/',
           'data_reduction_fallback_host%': 'http://compress.googlezip.net:80/',
         }],
@@ -1118,6 +1121,7 @@
     'spdy_proxy_auth_property%': '<(spdy_proxy_auth_property)',
     'spdy_proxy_auth_value%': '<(spdy_proxy_auth_value)',
     'data_reduction_proxy_probe_url%': '<(data_reduction_proxy_probe_url)',
+    'data_reduction_proxy_warmup_url%': '<(data_reduction_proxy_warmup_url)',
     'data_reduction_proxy_ssl_origin%' : '<(data_reduction_proxy_ssl_origin)',
     'data_reduction_proxy_alt_origin%' : '<(data_reduction_proxy_alt_origin)',
     'data_reduction_proxy_alt_fallback_origin%' : '<(data_reduction_proxy_alt_fallback_origin)',
@@ -2752,6 +2756,10 @@
         'defines': [
           'DATA_REDUCTION_PROXY_PROBE_URL="<(data_reduction_proxy_probe_url)"'],
       }],
+      ['data_reduction_proxy_warmup_url != ""', {
+        'defines': [
+          'DATA_REDUCTION_PROXY_WARMUP_URL="<(data_reduction_proxy_warmup_url)"'],
+      }],
       ['data_reduction_proxy_ssl_origin != ""', {
         'defines': [
           'DATA_REDUCTION_PROXY_SSL_ORIGIN="<(data_reduction_proxy_ssl_origin)"'],
diff --git a/chrome/browser/net/chrome_network_delegate.cc b/chrome/browser/net/chrome_network_delegate.cc
index 72ec539..c8fce3a 100644
--- a/chrome/browser/net/chrome_network_delegate.cc
+++ b/chrome/browser/net/chrome_network_delegate.cc
@@ -461,9 +461,11 @@ int ChromeNetworkDelegate::OnBeforeURLRequest(
   // only non-null profiles are considered.
   if (first_request_ && profile_) {
     bool record_timing = true;
-#if defined(DATA_REDUCTION_PROXY_PROBE_URL)
-    record_timing = (request->url() != GURL(DATA_REDUCTION_PROXY_PROBE_URL));
-#endif
+    if (data_reduction_proxy_params_) {
+      record_timing =
+          (request->url() != data_reduction_proxy_params_->probe_url()) &&
+          (request->url() != data_reduction_proxy_params_->warmup_url());
+    }
     if (record_timing) {
       first_request_ = false;
       net::LoadTimingInfo timing_info;
diff --git a/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_unittest_android.cc b/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_unittest_android.cc
index 65d97d9..84ff76d 100644
--- a/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_unittest_android.cc
+++ b/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_unittest_android.cc
@@ -45,7 +45,7 @@ void data_reduction_proxy::DataReductionProxySettingsTestBase::ResetSettings(
   EXPECT_CALL(*settings, GetLocalStatePrefs())
       .Times(AnyNumber())
       .WillRepeatedly(Return(&pref_service_));
-  EXPECT_CALL(*settings, GetURLFetcher()).Times(0);
+  EXPECT_CALL(*settings, GetURLFetcherForAvailabilityCheck()).Times(0);
   EXPECT_CALL(*settings, LogProxyState(_, _, _)).Times(0);
   settings_.reset(settings);
 }
@@ -53,6 +53,7 @@ void data_reduction_proxy::DataReductionProxySettingsTestBase::ResetSettings(
 template <class C>
 void data_reduction_proxy::DataReductionProxySettingsTestBase::SetProbeResult(
     const std::string& test_url,
+    const std::string& warmup_test_url,
     const std::string& response,
     ProbeURLFetchResult result,
     bool success,
@@ -60,11 +61,11 @@ void data_reduction_proxy::DataReductionProxySettingsTestBase::SetProbeResult(
   MockDataReductionProxySettings<C>* settings =
       static_cast<MockDataReductionProxySettings<C>*>(settings_.get());
   if (0 == expected_calls) {
-    EXPECT_CALL(*settings, GetURLFetcher()).Times(0);
+    EXPECT_CALL(*settings, GetURLFetcherForAvailabilityCheck()).Times(0);
     EXPECT_CALL(*settings, RecordProbeURLFetchResult(_)).Times(0);
   } else {
     EXPECT_CALL(*settings, RecordProbeURLFetchResult(result)).Times(1);
-    EXPECT_CALL(*settings, GetURLFetcher())
+    EXPECT_CALL(*settings, GetURLFetcherForAvailabilityCheck())
         .Times(expected_calls)
         .WillRepeatedly(Return(new net::FakeURLFetcher(
             GURL(test_url),
@@ -86,6 +87,7 @@ data_reduction_proxy::DataReductionProxySettingsTestBase::ResetSettings<
 template void
 data_reduction_proxy::DataReductionProxySettingsTestBase::SetProbeResult<
     DataReductionProxySettingsAndroid>(const std::string& test_url,
+                                       const std::string& warmup_test_url,
                                        const std::string& response,
                                        ProbeURLFetchResult result,
                                        bool success,
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc b/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc
index 16e0d20..d3a3890 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_params.cc
@@ -199,6 +199,8 @@ void DataReductionProxyParams::InitWithoutChecks() {
 
   std::string probe_url = command_line.GetSwitchValueASCII(
       switches::kDataReductionProxyProbeURL);
+  std::string warmup_url = command_line.GetSwitchValueASCII(
+      switches::kDataReductionProxyWarmupURL);
 
   // Set from preprocessor constants those params that are not specified on the
   // command line.
@@ -216,6 +218,8 @@ void DataReductionProxyParams::InitWithoutChecks() {
     alt_fallback_origin = GetDefaultAltFallbackOrigin();
   if (probe_url.empty())
     probe_url = GetDefaultProbeURL();
+  if (warmup_url.empty())
+    warmup_url = GetDefaultWarmupURL();
 
   origin_ = GURL(origin);
   fallback_origin_ = GURL(fallback_origin);
@@ -223,6 +227,7 @@ void DataReductionProxyParams::InitWithoutChecks() {
   alt_origin_ = GURL(alt_origin);
   alt_fallback_origin_ = GURL(alt_fallback_origin);
   probe_url_ = GURL(probe_url);
+  warmup_url_ = GURL(warmup_url);
 
 }
 
@@ -342,4 +347,11 @@ std::string DataReductionProxyParams::GetDefaultProbeURL() const {
   return std::string();
 }
 
+std::string DataReductionProxyParams::GetDefaultWarmupURL() const {
+#if defined(DATA_REDUCTION_PROXY_WARMUP_URL)
+  return DATA_REDUCTION_PROXY_WARMUP_URL;
+#endif
+  return std::string();
+}
+
 }  // namespace data_reduction_proxy
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_params.h b/components/data_reduction_proxy/browser/data_reduction_proxy_params.h
index 0285001..5ae00b8 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_params.h
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_params.h
@@ -58,8 +58,8 @@ class DataReductionProxyParams {
   // bypassed or disabled. If |kAlternativeAllowed| then an alternative proxy
   // configuration is allowed to be used. This alternative configuration would
   // replace the primary and fallback proxy configurations if enabled. Finally
-  // if |kPromoAllowed|, the client may show a promotion for the data
-  // reduction proxy.
+  // if |kPromoAllowed|, the client may show a promotion for the data reduction
+  // proxy.
   //
   // A standard configuration has a primary proxy, and a fallback proxy for
   // HTTP traffic. The alternative configuration has a different primary and
@@ -119,6 +119,11 @@ class DataReductionProxyParams {
     return probe_url_;
   }
 
+  // Returns the URL to fetch to warm the data reduction proxy connection.
+  const GURL& warmup_url() const {
+    return warmup_url_;
+  }
+
   // Set the proxy authentication key.
   void set_key(const std::string& key) {
     key_ = key;
@@ -180,6 +185,7 @@ class DataReductionProxyParams {
   virtual std::string GetDefaultAltOrigin() const;
   virtual std::string GetDefaultAltFallbackOrigin() const;
   virtual std::string GetDefaultProbeURL() const;
+  virtual std::string GetDefaultWarmupURL() const;
 
  private:
   GURL origin_;
@@ -188,6 +194,7 @@ class DataReductionProxyParams {
   GURL alt_origin_;
   GURL alt_fallback_origin_;
   GURL probe_url_;
+  GURL warmup_url_;
 
   std::string key_;
 
@@ -196,7 +203,6 @@ class DataReductionProxyParams {
   bool alt_allowed_;
   const bool promo_allowed_;
 
-
   DISALLOW_COPY_AND_ASSIGN(DataReductionProxyParams);
 };
 
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 5fc9213e..dc87a52 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 +304,13 @@ 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;
+
+  DCHECK(source == fetcher_.get());
   net::URLRequestStatus status = source->GetStatus();
   if (status.status() == net::URLRequestStatus::FAILED &&
       status.error() == net::ERR_INTERNET_DISCONNECTED) {
@@ -399,6 +406,7 @@ void DataReductionProxySettings::OnIPAddressChanged() {
   if (enabled_by_user_) {
     DCHECK(params_->allowed());
     ProbeWhetherDataReductionProxyIsAvailable();
+    WarmProxyConnection();
   }
 }
 
@@ -451,8 +459,10 @@ 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 +591,15 @@ 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;
@@ -595,12 +608,32 @@ net::URLFetcher* DataReductionProxySettings::GetURLFetcher() {
   return fetcher;
 }
 
+
+net::URLFetcher*
+DataReductionProxySettings::GetURLFetcherForAvailabilityCheck() {
+  return GetBaseURLFetcher(params_->probe_url(),
+                           net::LOAD_DISABLE_CACHE | net::LOAD_BYPASS_PROXY);
+}
+
+
 void DataReductionProxySettings::ProbeWhetherDataReductionProxyIsAvailable() {
-  net::URLFetcher* fetcher = GetURLFetcher();
+  net::URLFetcher* fetcher = GetURLFetcherForAvailabilityCheck();
   if (!fetcher)
     return;
   fetcher_.reset(fetcher);
   fetcher_->Start();
 }
 
+net::URLFetcher* DataReductionProxySettings::GetURLFetcherForWarmup() {
+  return GetBaseURLFetcher(params_->warmup_url(), net::LOAD_DISABLE_CACHE);
+}
+
+void DataReductionProxySettings::WarmProxyConnection() {
+  net::URLFetcher* fetcher = GetURLFetcherForWarmup();
+  if (!fetcher)
+    return;
+  warmup_fetcher_.reset(fetcher);
+  warmup_fetcher_->Start();
+}
+
 }  // namespace data_reduction_proxy
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_settings.h b/components/data_reduction_proxy/browser/data_reduction_proxy_settings.h
index c7fb154..eb68f67 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_settings.h
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_settings.h
@@ -173,7 +173,13 @@ class DataReductionProxySettings
  protected:
   void InitPrefMembers();
 
-  virtual net::URLFetcher* GetURLFetcher();
+  // Returns a fetcher for the probe to check if OK for the proxy to use SPDY.
+  // Virtual for testing.
+  virtual net::URLFetcher* GetURLFetcherForAvailabilityCheck();
+
+  // Returns a fetcher to warm up the connection to the data reduction proxy.
+  // Virtual for testing.
+  virtual net::URLFetcher* GetURLFetcherForWarmup();
 
   // Virtualized for unit test support.
   virtual PrefService* GetOriginalProfilePrefs();
@@ -273,6 +279,12 @@ class DataReductionProxySettings
   // failure.
   void ProbeWhetherDataReductionProxyIsAvailable();
 
+  // Warms the connection to the data reduction proxy.
+  void WarmProxyConnection();
+
+  // Generic method to get a URL fetcher.
+  net::URLFetcher* GetBaseURLFetcher(const GURL& gurl, int load_flags);
+
   // Returns a UTF16 string that's the hash of the configured authentication
   // |key| and |salt|. Returns an empty UTF16 string if no key is configured or
   // the data reduction proxy feature isn't available.
@@ -284,6 +296,8 @@ class DataReductionProxySettings
   bool enabled_by_user_;
 
   scoped_ptr<net::URLFetcher> fetcher_;
+  scoped_ptr<net::URLFetcher> warmup_fetcher_;
+
   BooleanPrefMember spdy_proxy_auth_enabled_;
   BooleanPrefMember data_reduction_proxy_alternative_enabled_;
 
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.cc b/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.cc
index a985683..62a5d4b 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.cc
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.cc
@@ -23,6 +23,7 @@ const char kDataReductionProxyFallback[] = "http://bar.com:80/";
 const char kDataReductionProxyKey[] = "12345";
 
 const char kProbeURLWithOKResponse[] = "http://ok.org/";
+const char kWarmupURLWithNoContentResponse[] = "http://warm.org/";
 
 const char kProxy[] = "proxy";
 
@@ -151,7 +152,8 @@ void DataReductionProxySettingsTestBase::ResetSettings(bool allowed,
   EXPECT_CALL(*settings, GetLocalStatePrefs())
       .Times(AnyNumber())
       .WillRepeatedly(Return(&pref_service_));
-  EXPECT_CALL(*settings, GetURLFetcher()).Times(0);
+  EXPECT_CALL(*settings, GetURLFetcherForAvailabilityCheck()).Times(0);
+  EXPECT_CALL(*settings, GetURLFetcherForWarmup()).Times(0);
   EXPECT_CALL(*settings, LogProxyState(_, _, _)).Times(0);
   settings_.reset(settings);
   settings_->configurator_.reset(new TestDataReductionProxyConfig());
@@ -165,6 +167,7 @@ DataReductionProxySettingsTestBase::ResetSettings<DataReductionProxySettings>(
 template <class C>
 void DataReductionProxySettingsTestBase::SetProbeResult(
     const std::string& test_url,
+    const std::string& warmup_test_url,
     const std::string& response,
     ProbeURLFetchResult result,
     bool success,
@@ -172,11 +175,12 @@ void DataReductionProxySettingsTestBase::SetProbeResult(
   MockDataReductionProxySettings<C>* settings =
       static_cast<MockDataReductionProxySettings<C>*>(settings_.get());
   if (0 == expected_calls) {
-    EXPECT_CALL(*settings, GetURLFetcher()).Times(0);
+    EXPECT_CALL(*settings, GetURLFetcherForAvailabilityCheck()).Times(0);
+    EXPECT_CALL(*settings, GetURLFetcherForWarmup()).Times(0);
     EXPECT_CALL(*settings, RecordProbeURLFetchResult(_)).Times(0);
   } else {
     EXPECT_CALL(*settings, RecordProbeURLFetchResult(result)).Times(1);
-    EXPECT_CALL(*settings, GetURLFetcher())
+    EXPECT_CALL(*settings, GetURLFetcherForAvailabilityCheck())
         .Times(expected_calls)
         .WillRepeatedly(Return(new net::FakeURLFetcher(
             GURL(test_url),
@@ -185,6 +189,15 @@ void DataReductionProxySettingsTestBase::SetProbeResult(
             success ? net::HTTP_OK : net::HTTP_INTERNAL_SERVER_ERROR,
             success ? net::URLRequestStatus::SUCCESS :
                       net::URLRequestStatus::FAILED)));
+    EXPECT_CALL(*settings, GetURLFetcherForWarmup())
+        .Times(expected_calls)
+        .WillRepeatedly(Return(new net::FakeURLFetcher(
+            GURL(warmup_test_url),
+            settings,
+            "",
+            success ? net::HTTP_NO_CONTENT : net::HTTP_INTERNAL_SERVER_ERROR,
+                success ? net::URLRequestStatus::SUCCESS :
+                          net::URLRequestStatus::FAILED)));
   }
 }
 
@@ -192,6 +205,7 @@ void DataReductionProxySettingsTestBase::SetProbeResult(
 template void
 DataReductionProxySettingsTestBase::SetProbeResult<DataReductionProxySettings>(
     const std::string& test_url,
+    const std::string& warmup_test_url,
     const std::string& response,
     ProbeURLFetchResult result,
     bool success,
@@ -212,6 +226,7 @@ void DataReductionProxySettingsTestBase::CheckProxyConfigs(
 void DataReductionProxySettingsTestBase::CheckProbe(
     bool initially_enabled,
     const std::string& probe_url,
+    const std::string& warmup_url,
     const std::string& response,
     bool request_succeeded,
     bool expected_enabled,
@@ -223,6 +238,7 @@ void DataReductionProxySettingsTestBase::CheckProbe(
     settings_->enabled_by_user_ = true;
   settings_->restricted_by_carrier_ = false;
   SetProbeResult(probe_url,
+                 warmup_url,
                  response,
                  FetchResult(initially_enabled,
                              request_succeeded && (response == "OK")),
@@ -237,11 +253,13 @@ void DataReductionProxySettingsTestBase::CheckProbe(
 
 void DataReductionProxySettingsTestBase::CheckProbeOnIPChange(
     const std::string& probe_url,
+    const std::string& warmup_url,
     const std::string& response,
     bool request_succeeded,
     bool expected_restricted,
     bool expected_fallback_restricted) {
   SetProbeResult(probe_url,
+                 warmup_url,
                  response,
                  FetchResult(!settings_->restricted_by_carrier_,
                              request_succeeded && (response == "OK")),
@@ -258,6 +276,7 @@ void DataReductionProxySettingsTestBase::CheckOnPrefChange(
     bool managed) {
   // Always have a sucessful probe for pref change tests.
   SetProbeResult(kProbeURLWithOKResponse,
+                 kWarmupURLWithNoContentResponse,
                  "OK",
                  FetchResult(enabled, true),
                  true,
@@ -277,6 +296,7 @@ void DataReductionProxySettingsTestBase::CheckInitDataReductionProxy(
     bool enabled_at_startup) {
   base::MessageLoopForUI loop;
   SetProbeResult(kProbeURLWithOKResponse,
+                 kWarmupURLWithNoContentResponse,
                  "OK",
                  FetchResult(enabled_at_startup, true),
                  true,
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.h b/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.h
index eae8bae..fbe4d45 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.h
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_settings_test_utils.h
@@ -61,7 +61,8 @@ class MockDataReductionProxySettings : public C {
           DataReductionProxyParams::kPromoAllowed)) {}
   MockDataReductionProxySettings<C>(int flags)
       : C(new DataReductionProxyParams(flags)) {}
-  MOCK_METHOD0(GetURLFetcher, net::URLFetcher*());
+  MOCK_METHOD0(GetURLFetcherForAvailabilityCheck, net::URLFetcher*());
+  MOCK_METHOD0(GetURLFetcherForWarmup, net::URLFetcher*());
   MOCK_METHOD0(GetOriginalProfilePrefs, PrefService*());
   MOCK_METHOD0(GetLocalStatePrefs, PrefService*());
   MOCK_METHOD3(LogProxyState, void(
@@ -107,11 +108,13 @@ class DataReductionProxySettingsTestBase : public testing::Test {
 
   template <class C> void SetProbeResult(
       const std::string& test_url,
+      const std::string& warmup_test_url,
       const std::string& response,
       ProbeURLFetchResult state,
       bool success,
       int expected_calls);
   virtual void SetProbeResult(const std::string& test_url,
+                              const std::string& warmup_test_url,
                               const std::string& response,
                               ProbeURLFetchResult result,
                               bool success,
@@ -122,12 +125,14 @@ class DataReductionProxySettingsTestBase : public testing::Test {
                          bool expected_fallback_restricted);
   void CheckProbe(bool initially_enabled,
                   const std::string& probe_url,
+                  const std::string& warmup_url,
                   const std::string& response,
                   bool request_success,
                   bool expected_enabled,
                   bool expected_restricted,
                   bool expected_fallback_restricted);
   void CheckProbeOnIPChange(const std::string& probe_url,
+                            const std::string& warmup_url,
                             const std::string& response,
                             bool request_success,
                             bool expected_enabled,
@@ -157,12 +162,18 @@ class ConcreteDataReductionProxySettingsTest
   }
 
   virtual void SetProbeResult(const std::string& test_url,
+                              const std::string& warmup_test_url,
                               const std::string& response,
                               ProbeURLFetchResult result,
                               bool success,
                               int expected_calls) OVERRIDE {
     return DataReductionProxySettingsTestBase::SetProbeResult<C>(
-  test_url, response, result, success, expected_calls);
+        test_url,
+        warmup_test_url,
+        response,
+        result,
+        success,
+        expected_calls);
   }
 };
 
diff --git a/components/data_reduction_proxy/browser/data_reduction_proxy_settings_unittest.cc b/components/data_reduction_proxy/browser/data_reduction_proxy_settings_unittest.cc
index fcb78fe..0dd2a6a 100644
--- a/components/data_reduction_proxy/browser/data_reduction_proxy_settings_unittest.cc
+++ b/components/data_reduction_proxy/browser/data_reduction_proxy_settings_unittest.cc
@@ -31,6 +31,7 @@ const char kDataReductionProxySSL[] = "http://ssl.com:80";
 const char kProbeURLWithOKResponse[] = "http://ok.org/";
 const char kProbeURLWithBadResponse[] = "http://bad.org/";
 const char kProbeURLWithNoResponse[] = "http://no.org/";
+const char kWarmupURLWithNoContentResponse[] = "http://warm.org/";
 
 }  // namespace
 
@@ -157,10 +158,10 @@ TEST_F(DataReductionProxySettingsTest, TestSetProxyConfigs) {
 
 TEST_F(DataReductionProxySettingsTest, TestIsProxyEnabledOrManaged) {
   settings_->InitPrefMembers();
-    base::MessageLoopForUI loop;
-    // The proxy is disabled initially.
-    settings_->enabled_by_user_ = false;
-    settings_->SetProxyConfigs(false, false, false, false);
+  base::MessageLoopForUI loop;
+  // The proxy is disabled initially.
+  settings_->enabled_by_user_ = false;
+  settings_->SetProxyConfigs(false, false, false, false);
 
   EXPECT_FALSE(settings_->IsDataReductionProxyEnabled());
   EXPECT_FALSE(settings_->IsDataReductionProxyManaged());
@@ -172,6 +173,8 @@ TEST_F(DataReductionProxySettingsTest, TestIsProxyEnabledOrManaged) {
   CheckOnPrefChange(true, true, true);
   EXPECT_TRUE(settings_->IsDataReductionProxyEnabled());
   EXPECT_TRUE(settings_->IsDataReductionProxyManaged());
+
+  base::MessageLoop::current()->RunUntilIdle();
 }
 
 TEST_F(DataReductionProxySettingsTest, TestAcceptableChallenges) {
@@ -309,14 +312,42 @@ TEST_F(DataReductionProxySettingsTest, TestMaybeActivateDataReductionProxy) {
   base::MessageLoopForUI loop;
   // The proxy is enabled and unrestructed initially.
   // Request succeeded but with bad response, expect proxy to be restricted.
-  CheckProbe(true, kProbeURLWithBadResponse, "Bad", true, true, true, false);
+  CheckProbe(true,
+             kProbeURLWithBadResponse,
+             kWarmupURLWithNoContentResponse,
+             "Bad",
+             true,
+             true,
+             true,
+             false);
   // Request succeeded with valid response, expect proxy to be unrestricted.
-  CheckProbe(true, kProbeURLWithOKResponse, "OK", true, true, false, false);
+  CheckProbe(true,
+             kProbeURLWithOKResponse,
+             kWarmupURLWithNoContentResponse,
+             "OK",
+             true,
+             true,
+             false,
+             false);
   // Request failed, expect proxy to be enabled but restricted.
-  CheckProbe(true, kProbeURLWithNoResponse, "", false, true, true, false);
+  CheckProbe(true,
+             kProbeURLWithNoResponse,
+             kWarmupURLWithNoContentResponse,
+             "",
+             false,
+             true,
+             true,
+             false);
   // The proxy is disabled initially. Probes should not be emitted to change
   // state.
-  CheckProbe(false, kProbeURLWithOKResponse, "OK", true, false, false, false);
+  CheckProbe(false,
+             kProbeURLWithOKResponse,
+             kWarmupURLWithNoContentResponse,
+             "OK",
+             true,
+             false,
+             false,
+             false);
 }
 
 TEST_F(DataReductionProxySettingsTest, TestOnIPAddressChanged) {
@@ -334,13 +365,33 @@ TEST_F(DataReductionProxySettingsTest, TestOnIPAddressChanged) {
   settings_->SetProxyConfigs(true, false, false, true);
   // IP address change triggers a probe that succeeds. Proxy remains
   // unrestricted.
-  CheckProbeOnIPChange(kProbeURLWithOKResponse, "OK", true, false, false);
+  CheckProbeOnIPChange(kProbeURLWithOKResponse,
+                       kWarmupURLWithNoContentResponse,
+                       "OK",
+                       true,
+                       false,
+                       false);
   // IP address change triggers a probe that fails. Proxy is restricted.
-  CheckProbeOnIPChange(kProbeURLWithBadResponse, "Bad", true, true, false);
+  CheckProbeOnIPChange(kProbeURLWithBadResponse,
+                       kWarmupURLWithNoContentResponse,
+                       "Bad",
+                       true,
+                       true,
+                       false);
   // IP address change triggers a probe that fails. Proxy remains restricted.
-  CheckProbeOnIPChange(kProbeURLWithBadResponse, "Bad", true, true, false);
+  CheckProbeOnIPChange(kProbeURLWithBadResponse,
+                       kWarmupURLWithNoContentResponse,
+                       "Bad",
+                       true,
+                       true,
+                       false);
   // IP address change triggers a probe that succeed. Proxy is unrestricted.
-  CheckProbeOnIPChange(kProbeURLWithBadResponse, "OK", true, false, false);
+  CheckProbeOnIPChange(kProbeURLWithBadResponse,
+                       kWarmupURLWithNoContentResponse,
+                       "OK",
+                       true,
+                       false,
+                       false);
 }
 
 TEST_F(DataReductionProxySettingsTest, TestOnProxyEnabledPrefChange) {
diff --git a/components/data_reduction_proxy/common/data_reduction_proxy_switches.cc b/components/data_reduction_proxy/common/data_reduction_proxy_switches.cc
index 780dbeb..1dd1df7 100644
--- a/components/data_reduction_proxy/common/data_reduction_proxy_switches.cc
+++ b/components/data_reduction_proxy/common/data_reduction_proxy_switches.cc
@@ -30,6 +30,10 @@ const char kDataReductionProxyKey[] = "spdy-proxy-auth-value";
 // proxy. Note this canary does not go through the data reduction proxy.
 const char kDataReductionProxyProbeURL[] = "data-reduction-proxy-probe-url";
 
+// Sets a URL to fetch to warm up the data reduction proxy on startup and
+// network changes.
+const char kDataReductionProxyWarmupURL[] = "data-reduction-proxy-warmup-url";
+
 // The origin of the data reduction SSL proxy.
 const char kDataReductionSSLProxy[] = "data-reduction-ssl-proxy";
 
diff --git a/components/data_reduction_proxy/common/data_reduction_proxy_switches.h b/components/data_reduction_proxy/common/data_reduction_proxy_switches.h
index 3a68011..837a07f 100644
--- a/components/data_reduction_proxy/common/data_reduction_proxy_switches.h
+++ b/components/data_reduction_proxy/common/data_reduction_proxy_switches.h
@@ -18,6 +18,7 @@ extern const char kDataReductionProxyDev[];
 extern const char kDataReductionProxyFallback[];
 extern const char kDataReductionProxyKey[];
 extern const char kDataReductionProxyProbeURL[];
+extern const char kDataReductionProxyWarmupURL[];
 extern const char kDataReductionSSLProxy[];
 extern const char kDisableDataReductionProxyDev[];
 extern const char kEnableDataReductionProxyDev[];