Simple fallback implementation.

chrome/browser/net/spdyproxy/data_reduction_proxy_settings_android.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_android.h"
 
 #include "base/android/build_info.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/base64.h"
@@ skipping 37 matching lines @@
 // New values should be added at the end before |NUM_SPDY_PROXY_AUTH_STATE|.
 enum {
   CHROME_STARTUP,
   SPDY_PROXY_AUTH_ON_AT_STARTUP,
   SPDY_PROXY_AUTH_ON_BY_USER,
   SPDY_PROXY_AUTH_OFF_BY_USER,
   // Used by UMA histograms and should always be the last value.
   NUM_SPDY_PROXY_AUTH_STATE
 };
 
+std::string ProtocolAndHost(std::string origin) {

[bengr, 2013/10/20 18:19:31]

Please add a comment that describes the format of the return. It's a little
strange that it includes a semicolon.

+  if (origin.empty()) {
+    return origin;
+  }
+  GURL url = GURL(origin);
+  std::string protocol = url.SchemeIsSecure() ? "HTTPS "  : "HTTP ";
+  return protocol + net::HostPortPair::FromURL(url).ToString() + "; ";
+}
+
 }  // namespace
 
 DataReductionProxySettingsAndroid::DataReductionProxySettingsAndroid(
     JNIEnv* env, jobject obj): DataReductionProxySettings() {
 }
 
 DataReductionProxySettingsAndroid::~DataReductionProxySettingsAndroid() {}
 
 void DataReductionProxySettingsAndroid::InitDataReductionProxySettings(
     JNIEnv* env,
@@ skipping 185 matching lines @@
 
 // TODO(bengr): Replace with our own ProxyResolver.
 std::string DataReductionProxySettingsAndroid::GetProxyPacScript() {
   // Compose the PAC-only bypass code; these will be URL patterns that
   // are matched by regular expression. Host bypasses are handled outside
   // of the PAC file using the regular proxy bypass list configs.
   std::string bypass_clause =
       "(" + JoinString(pac_bypass_rules_, ") || (") + ")";
 
   // Generate a proxy PAC that falls back to direct loading when the proxy is
-  // unavailable and only process HTTP traffic. (With a statically configured
-  // proxy, proxy failures will simply result in a connection error presented to
-  // users.)
+  // unavailable and only process HTTP traffic.
 
-  std::string proxy_host =
-      DataReductionProxySettings::GetDataReductionProxyOriginHostPort();
+  std::string proxy_host = ProtocolAndHost(
+      DataReductionProxySettings::GetDataReductionProxyOrigin());
+  std::string fallback_host = ProtocolAndHost(
+      DataReductionProxySettings::GetDataReductionProxyFallback());
   std::string pac = "function FindProxyForURL(url, host) {"
       "  if (" + bypass_clause + ") {"
       "    return 'DIRECT';"
       "  } "
       "  if (url.substring(0, 5) == 'http:') {"
-      "    return 'HTTPS " + proxy_host +
-      "; DIRECT';"
+      "    return '" + proxy_host + fallback_host + "DIRECT';"
       "  }"
       "  return 'DIRECT';"
       "}";
   return pac;
 }
 
 // Used by generated jni code.
 static jint Init(JNIEnv* env, jobject obj) {
   DataReductionProxySettingsAndroid* settings =
       new DataReductionProxySettingsAndroid(env, obj);
   return reinterpret_cast<jint>(settings);
 }