Implement simple http server with set cookie functionality.

ios/web/public/test/response_providers/html_response_provider.h

Index: ios/web/public/test/response_providers/html_response_provider.h
diff --git a/ios/web/public/test/response_providers/html_response_provider.h b/ios/web/public/test/response_providers/html_response_provider.h
index 26f0020b728b115a38e52944dd3a8f18e5e791ef..933b32be73f7c1102fa79703598e853432613880 100644
--- a/ios/web/public/test/response_providers/html_response_provider.h
+++ b/ios/web/public/test/response_providers/html_response_provider.h
@@ -26,6 +26,10 @@ class HtmlResponseProvider : public web::DataResponseProvider {
   // Constructs an HtmlResponseProvider that generates a simple string response
   // to a URL based on the mapping present in |responses|.
   explicit HtmlResponseProvider(const std::map<GURL, std::string>& responses);
+  // Constructs an HtmlResponseProvider that generates a simple string response
+  // to a URL based on the mapping present in |responses| and |cookie|.
+  explicit HtmlResponseProvider(const std::map<GURL, std::string>& responses,
+                                const std::string& cookie);

[pkl (ping after 24h if needed), 2016/08/30 21:24:04]

I don't think "explicit" on a constructor w/ more than 1 parameter means
anything. Do you?
See HtmlResponseProviderImpl as well.

[liaoyuke, 2016/09/12 18:58:13]

Done.

   // Constructs an HtmlResponseProvider that generates a response to a URL based
   // on the mapping present in |responses|.
   explicit HtmlResponseProvider(