Modify data_reduction_proxy_header to support tamper detection logic.

components/data_reduction_proxy/common/data_reduction_proxy_headers.h

Index: components/data_reduction_proxy/common/data_reduction_proxy_headers.h
diff --git a/components/data_reduction_proxy/common/data_reduction_proxy_headers.h b/components/data_reduction_proxy/common/data_reduction_proxy_headers.h
index 88b0cd054b8423d83d01beeb78fe7d0be5a6ce6d..f356df6d164681bf3949d156714aa9c63b5ede32 100644
--- a/components/data_reduction_proxy/common/data_reduction_proxy_headers.h
+++ b/components/data_reduction_proxy/common/data_reduction_proxy_headers.h
@@ -37,8 +37,12 @@ bool GetDataReductionProxyInfo(
     DataReductionProxyInfo* proxy_info);
 
 // Returns true if the response contain the data reduction proxy Via header
-// value. Used to check the integrity of data reduction proxy responses.
-bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers);
+// value. If data reduction proxy Via header value exists, set |is_the_last|

[bengr, 2014/07/16 19:23:56]

I can't parse this comment. How about:

// Returns true if the response contains the data reduction proxy Via header 
// value. If non-NULL, sets |has_intermediary| to true if another server added a

// Via header after the data reduction proxy, and to false otherwise.

Also, change is_the_last to has_intermediary

[xingx, 2014/07/16 21:22:33]

Done.

+// as whether it occurs at the last if |is_the_last| is not NULL. Used to check
+// the integrity of data reduction proxy responses and whether there are other
+// middleboxes between data reduction proxy and chrome.
+bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers,
+                                    bool* is_the_last);
 
 // Returns the reason why the Chrome proxy should be bypassed or not, and
 // populates |proxy_info| with information on how long to bypass if
@@ -48,6 +52,14 @@ GetDataReductionProxyBypassEventType(
     const net::HttpResponseHeaders* headers,
     DataReductionProxyInfo* proxy_info);
 
+// Searches for the specified Chrome-Proxy action, and if present saves its
+// value as a string in |action_value|. Only keeps the first one and ignores
+// the rest if multiple actions match |action_prefix|.
+bool GetDataReductionProxyActionValue(
+    const net::HttpResponseHeaders* headers,
+    const std::string& action_prefix,
+    std::string* action_value);
+
 // Searches for the specified Chrome-Proxy action, and if present interprets
 // its value as a duration in seconds.
 bool GetDataReductionProxyBypassDuration(