Add Network.setSendRequestIdHeader and use it in headless

headless/public/util/testing/generic_url_request_mocks.h

Index: headless/public/util/testing/generic_url_request_mocks.h
diff --git a/headless/public/util/testing/generic_url_request_mocks.h b/headless/public/util/testing/generic_url_request_mocks.h
index 4727961681deb9055e6c63efad03ab35c1d9eef3..8483e569139dac00dc064587aa8d297dca03951c 100644
--- a/headless/public/util/testing/generic_url_request_mocks.h
+++ b/headless/public/util/testing/generic_url_request_mocks.h
@@ -25,16 +25,19 @@ class MockGenericURLRequestJobDelegate : public GenericURLRequestJob::Delegate {
 
   bool BlockOrRewriteRequest(
       const GURL& url,
+      const std::string& devtools_id,
       const std::string& method,
       const std::string& referrer,
       GenericURLRequestJob::RewriteCallback callback) override;
 
   const GenericURLRequestJob::HttpResponse* MaybeMatchResource(
       const GURL& url,
+      const std::string& devtools_id,
       const std::string& method,
       const net::HttpRequestHeaders& request_headers) override;
 
   void OnResourceLoadComplete(const GURL& final_url,
+                              const std::string& devtools_id,
                               const std::string& mime_type,
                               int http_response_code) override;