Support for new data reduction proxy via header

chrome/renderer/page_load_histograms.cc

Index: chrome/renderer/page_load_histograms.cc
diff --git a/chrome/renderer/page_load_histograms.cc b/chrome/renderer/page_load_histograms.cc
index 6ce21e24031130bec14e039ac58dd12542ea7a3e..66db91ec7ac5da11c7cae4794932d5e0ff036ab2 100644
--- a/chrome/renderer/page_load_histograms.cc
+++ b/chrome/renderer/page_load_histograms.cc
@@ -32,6 +32,10 @@
 #include "third_party/WebKit/public/web/WebView.h"
 #include "url/gurl.h"
 
+#if defined(SPDY_PROXY_AUTH_ORIGIN)
+#include "net/http/http_response_headers.h"
+#endif
+
 using blink::WebDataSource;
 using blink::WebFrame;
 using blink::WebPerformance;
@@ -191,13 +195,51 @@ bool ViaHeaderContains(WebFrame* frame, const std::string& via_value) {
 
 // Returns true if the data reduction proxy was used. Note, this function will
 // produce a false positive if a page is fetched using SPDY and using a proxy,
-// and |kDatReductionProxyViaValue| is added to the Via header.
-// TODO(bengr): Plumb the hostname of the proxy from |HttpNetworkTransaction|
-// and check if it matches |SPDY_PROXY_AUTH_ORIGIN|.
+// and the data reduction proxy's via value is added to the Via header.
+// TODO(bengr): Plumb the hostname of the proxy and check if it matches
+// |SPDY_PROXY_AUTH_ORIGIN|.
 bool DataReductionProxyWasUsed(WebFrame* frame) {
 #if defined(SPDY_PROXY_AUTH_ORIGIN)
-  const char kDatReductionProxyViaValue[] = "1.1 Chrome Compression Proxy";
-  return ViaHeaderContains(frame, kDatReductionProxyViaValue);
+  DocumentState* document_state =
+      DocumentState::FromDataSource(frame->dataSource());
+  if (!document_state->was_fetched_via_proxy())
+    return false;
+
+  std::string via_header =
+      base::UTF16ToUTF8(frame->dataSource()->response().httpHeaderField("Via"));
+
+  if (via_header.empty())
+    return false;
+  std::string headers = "HTTP/1.1 200 OK\nVia: " + via_header + "\n\n";
+  std::replace(headers.begin(), headers.end(), '\n', '\0');
+  scoped_refptr<net::HttpResponseHeaders> response_headers(
+      new net::HttpResponseHeaders(headers));
+
+  // TODO(bengr): Remove duplication of this code in DataReductionProxySettings
+  // and HttpNetworkTransaction.
+  const size_t kVersionSize = 4;
+  const char kDataReductionProxyViaValue[] = "Chrome-Compression-Proxy";
+  size_t value_len = strlen(kDataReductionProxyViaValue);
+  void* iter = NULL;
+  std::string value;
+
+  // Case-sensitive comparison. Assumes the received protocol and the space
+  // following it are always |kVersionSize| characters. E.g.,
+  // 'Via: 1.1 Chrome-Compression-Proxy'
+  while (response_headers->EnumerateHeader(&iter, "via", &value)) {
+    if (!value.compare(kVersionSize, value_len, kDataReductionProxyViaValue))
+      return true;
+  }
+
+  // TODO(bengr): Remove deprecated header value.
+  const char kDeprecatedDataReductionProxyViaValue[] =
+      "1.1 Chrome Compression Proxy";
+  iter = NULL;
+  while (response_headers->EnumerateHeader(&iter, "via", &value))
+    if (value == kDeprecatedDataReductionProxyViaValue) return true;
+
+  return false;
+
 #endif
   return false;
 }