Simple fallback implementation.

chrome/browser/net/spdyproxy/data_reduction_proxy_settings_android.cc

Index: chrome/browser/net/spdyproxy/data_reduction_proxy_settings_android.cc
diff --git a/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_android.cc b/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_android.cc
index 2c23fbff129edd09db973256d4673c68c5d3668a..d084f578dd0cc08e9fdec03e73acfe5ca4095324 100644
--- a/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_android.cc
+++ b/chrome/browser/net/spdyproxy/data_reduction_proxy_settings_android.cc
@@ -55,6 +55,15 @@ enum {
   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(
@@ -260,19 +269,18 @@ std::string DataReductionProxySettingsAndroid::GetProxyPacScript() {
       "(" + 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';"
       "}";