Simple fallback implementation.

chrome/browser/net/spdyproxy/data_reduction_proxy_settings.cc

 // Copyright 2013 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/net/spdyproxy/data_reduction_proxy_settings.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
@@ skipping 132 matching lines @@
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kSpdyProxyAuthOrigin))
     return command_line.GetSwitchValueASCII(switches::kSpdyProxyAuthOrigin);
 #if defined(SPDY_PROXY_AUTH_ORIGIN)
   return SPDY_PROXY_AUTH_ORIGIN;
 #else
   return std::string();
 #endif
 }
 
+std::string DataReductionProxySettings::GetDataReductionProxyFallback() {
+  // Regardless of what else is defined, only return a value if the main proxy
+  // origin is defined.
+  if (GetDataReductionProxyOrigin().empty())
+    return std::string();
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+  if (command_line.HasSwitch(switches::kSpdyProxyAuthFallback))
+    return command_line.GetSwitchValueASCII(switches::kSpdyProxyAuthFallback);
+#if defined(DATA_REDUCTION_FALLBACK_HOST)
+  return DATA_REDUCTION_FALLBACK_HOST;
+#else
+  return std::string();
+#endif
+}
+
 std::string DataReductionProxySettings::GetDataReductionProxyAuth() {
   if (!IsDataReductionProxyAllowed())
     return std::string();
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kSpdyProxyAuthOrigin)) {
     // If an origin is provided via a switch, then only consider the value
     // that is provided by a switch. Do not use the preprocessor constant.
     // Don't expose SPDY_PROXY_AUTH_VALUE to a proxy passed in via the command
     // line.
     if (command_line.HasSwitch(switches::kSpdyProxyAuthValue))
@@ skipping 67 matching lines @@
   }
   DVLOG(1) << "The data reduction proxy is blocked.";
 
   if (enabled_by_user_ && !disabled_by_carrier_) {
     // Disable the proxy.
     SetProxyConfigs(false, false);
   }
   disabled_by_carrier_ = true;
 }
 
-std::string DataReductionProxySettings::GetDataReductionProxyOriginHostPort() {
-  std::string spdy_proxy = GetDataReductionProxyOrigin();
-  if (spdy_proxy.empty()) {
-    DLOG(ERROR) << "A SPDY proxy has not been set.";
-    return spdy_proxy;
-  }
-  // Remove a trailing slash from the proxy string if one exists as well as
-  // leading HTTPS scheme.
-  return net::HostPortPair::FromURL(GURL(spdy_proxy)).ToString();
-}
-
 void DataReductionProxySettings::OnIPAddressChanged() {
   if (enabled_by_user_) {
     DCHECK(IsDataReductionProxyAllowed());
     ProbeWhetherDataReductionProxyIsAvailable();
   }
 }
 
 void DataReductionProxySettings::OnProxyEnabledPrefChange() {
   if (!IsDataReductionProxyAllowed())
     return;
@@ skipping 56 matching lines @@
   PrefService* prefs = GetOriginalProfilePrefs();
 
   // TODO(marq): Consider moving this so stats are wiped the first time the
   // proxy settings are actually (not maybe) turned on.
   if (spdy_proxy_auth_enabled_.GetValue() &&
       !prefs->GetBoolean(prefs::kSpdyProxyAuthWasEnabledBefore)) {
     prefs->SetBoolean(prefs::kSpdyProxyAuthWasEnabledBefore, true);
     ResetDataReductionStatistics();
   }
 
-  std::string spdy_proxy_origin = GetDataReductionProxyOriginHostPort();
-
+  std::string proxy = GetDataReductionProxyOrigin();
   // Configure use of the data reduction proxy if it is enabled and the proxy
   // origin is non-empty.
-  enabled_by_user_=
-      spdy_proxy_auth_enabled_.GetValue() && !spdy_proxy_origin.empty();
+  enabled_by_user_= spdy_proxy_auth_enabled_.GetValue() && !proxy.empty();
   SetProxyConfigs(enabled_by_user_ && !disabled_by_carrier_, at_startup);
 
   // Check if the proxy has been disabled explicitly by the carrier.
   if (enabled_by_user_)
     ProbeWhetherDataReductionProxyIsAvailable();
 }
 
 void DataReductionProxySettings::SetProxyConfigs(bool enabled,
                                                  bool at_startup) {
   LogProxyState(enabled, at_startup);
   PrefService* prefs = GetOriginalProfilePrefs();
   DCHECK(prefs);
   DictionaryPrefUpdate update(prefs, prefs::kProxy);
   base::DictionaryValue* dict = update.Get();
   if (enabled) {
+    std::string fallback = GetDataReductionProxyFallback();
     std::string proxy_server_config =
-        "http=" + GetDataReductionProxyOrigin() + ",direct://;";
+        "http=" + GetDataReductionProxyOrigin() +
+        (fallback.empty() ? "" : "," + fallback) +
+        ",direct://;";
     dict->SetString("server", proxy_server_config);
     dict->SetString("mode",
                     ProxyModeToString(ProxyPrefs::MODE_FIXED_SERVERS));
     dict->SetString("bypass_list", JoinString(bypass_rules_, ", "));
   } else {
     dict->SetString("mode", ProxyModeToString(ProxyPrefs::MODE_SYSTEM));
     dict->SetString("server", "");
     dict->SetString("bypass_list", "");
   }
 }
@@ skipping 95 matching lines @@
 }
 
 void
 DataReductionProxySettings::ProbeWhetherDataReductionProxyIsAvailable() {
   net::URLFetcher* fetcher = GetURLFetcher();
   if (!fetcher)
     return;
   fetcher_.reset(fetcher);
   fetcher_->Start();
 }