Expose data reduction proxy auth token for internal builds.

google_apis/google_api_keys.h

Index: google_apis/google_api_keys.h
diff --git a/google_apis/google_api_keys.h b/google_apis/google_api_keys.h
index 5acdf263a6ffb9c58c191df6accbc567c6040abf..b2399bf980d7836218b601ed530bf3449d0406cf 100644
--- a/google_apis/google_api_keys.h
+++ b/google_apis/google_api_keys.h
@@ -90,6 +90,9 @@ std::string GetOAuth2ClientID(OAuth2Client client);
 // in, e.g. URL-escaped if you use it in a URL.
 std::string GetOAuth2ClientSecret(OAuth2Client client);
 
+// Returns the auth token for the data reduction proxy.
+std::string GetSpdyProxyAuthValue();
+
 // Returns if the API key using in the current build is the one for official
 // Google Chrome.
 bool IsGoogleChromeAPIKeyUsed();