[Android WebView] Provide a response header for application-provided content

android_webview/browser/net/android_stream_reader_url_request_job.cc

Index: android_webview/browser/net/android_stream_reader_url_request_job.cc
diff --git a/android_webview/browser/net/android_stream_reader_url_request_job.cc b/android_webview/browser/net/android_stream_reader_url_request_job.cc
index 07106d46916cd994166c055da28b3a90f0fdab0a..d7b407ecc7c1149a671fb0597fc37f88b3ddb58c 100644
--- a/android_webview/browser/net/android_stream_reader_url_request_job.cc
+++ b/android_webview/browser/net/android_stream_reader_url_request_job.cc
@@ -41,6 +41,8 @@ namespace {
 const int kHTTPOk = 200;
 const int kHTTPNotFound = 404;
 
+const char kResponseHeaderViaShouldInterceptRequest[] =
+    "Client-Via: shouldInterceptRequest";
 const char kHTTPOkText[] = "OK";
 const char kHTTPNotFoundText[] = "Not Found";
 
@@ -322,6 +324,9 @@ void AndroidStreamReaderURLRequestJob::HeadersComplete(
     }
   }
 
+  // Indicate that the response had been obtained via shouldInterceptRequest.
+  headers->AddHeader(kResponseHeaderViaShouldInterceptRequest);
+
   response_info_.reset(new net::HttpResponseInfo());
   response_info_->headers = headers;