Add Brotli to Accept Encoding header for secure DRP requests

components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.h

Index: components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.h
diff --git a/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.h b/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.h
index fa56f3ce7e64ea0a141b253a468bb7b8d7445e83..c1b51635e799ae1958ced5382a267a06f41f8725 100644
--- a/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.h
+++ b/components/data_reduction_proxy/core/browser/data_reduction_proxy_network_delegate.h
@@ -87,6 +87,8 @@ class DataReductionProxyNetworkDelegate : public net::LayeredNetworkDelegate {
       std::unique_ptr<DataUseGroupProvider> data_use_group_provider);
 
  private:
+  friend class DataReductionProxyTestContext;
+
   // Resets if Lo-Fi has been used for the last main frame load to false.
   void OnBeforeURLRequestInternal(net::URLRequest* request,
                                   const net::CompletionCallback& callback,
@@ -153,6 +155,13 @@ class DataReductionProxyNetworkDelegate : public net::LayeredNetworkDelegate {
       const net::ProxyInfo& proxy_info,
       const net::ProxyRetryInfoMap& proxy_retry_info) const;
 
+  // May add Brotli to Accept Encoding request header if |proxy_info| contains
+  // a proxy server that is expected to support Brotli encoding.
+  void MaybeAddBrotliToAcceptEncodingHeader(
+      const net::ProxyInfo& proxy_info,
+      net::HttpRequestHeaders* request_headers,
+      const net::URLRequest& request) const;
+
   // Total size of all content that has been received over the network.
   int64_t total_received_bytes_;
 
@@ -172,6 +181,10 @@ class DataReductionProxyNetworkDelegate : public net::LayeredNetworkDelegate {
 
   std::unique_ptr<DataUseGroupProvider> data_use_group_provider_;
 
+  // If |exclude_chrome_proxy_header_for_testing_| is set to true, chrome-proxy
+  // header would not be added to the request headers.
+  bool exclude_chrome_proxy_header_for_testing_;
+
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(DataReductionProxyNetworkDelegate);