Make DRP bypass logic apply to any proxies that send the DRP via header.

components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.cc

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.cc
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.cc b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.cc
index b2260502ed8fb5cbe3004fe2764c9c3267b98850..3d942ff1ef3972b7763e7b6818c82434541ea6c1 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.cc
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_bypass_protocol.cc
@@ -90,13 +90,29 @@ bool DataReductionProxyBypassProtocol::MaybeBypassProxyAndPrepareToRetry(
 
   // Empty implies either that the request was served from cache or that
   // request was served directly from the origin.
+  // TODO(sclittle): Add UMA to confirm that the |proxy_server| is never empty
+  // when the response has the Data Reduction Proxy via header.
   if (request->proxy_server().IsEmpty())
     return false;
 
   DataReductionProxyTypeInfo data_reduction_proxy_type_info;
   if (!config_->WasDataReductionProxyUsed(request,
                                           &data_reduction_proxy_type_info)) {
-    return false;
+    if (!HasDataReductionProxyViaHeader(response_headers, nullptr))
+      return false;
+
+    // If the |proxy_server| doesn't match any of the currently configured Data
+    // Reduction Proxies, but it still has the Data Reduction Proxy via header,
+    // then apply the bypass logic regardless.
+    // TODO(sclittle): Add UMA to record how often this occurs, and remove this
+    // workaround once http://crbug.com/476610 is fixed.
+    data_reduction_proxy_type_info.proxy_servers.first = net::ProxyServer(
+        net::ProxyServer::SCHEME_HTTPS, request->proxy_server());
+    data_reduction_proxy_type_info.proxy_servers.second = net::ProxyServer(
+        net::ProxyServer::SCHEME_HTTP, request->proxy_server());
+    data_reduction_proxy_type_info.is_alternative = false;
+    data_reduction_proxy_type_info.is_fallback = false;
+    data_reduction_proxy_type_info.is_ssl = request->url().SchemeIsSecure();

[jeremyim, 2015/05/11 22:32:52]

If there have been instances of HTTPS requests hitting this issue, then this
will continue to fail, since we return false if is_ssl is true (line 119)

[sclittle, 2015/05/11 22:44:11]

True, but we don't support bypass for the HTTPS tunneling proxy anyways, and
IIUC there's no way the proxy could have added the via header for an HTTPS
response anyways.

This conditional set of |is_ssl| is essentially just here for clarity's sake,
since request->url().SchemeIsSecure() will always be false here. This code
doesn't require it to be false though, so I don't want to put a DCHECK and force
is_ssl = false.

   }
   // TODO(bengr): Implement bypass for CONNECT tunnel.
   if (data_reduction_proxy_type_info.is_ssl)