Adds support for POST request with bodies on WKWebView.

ios/web/web_state/js/crw_js_post_request_loader.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IOS_WEB_WEB_STATE_JS_CRW_JS_POST_REQUEST_LOADER_H_
+#define IOS_WEB_WEB_STATE_JS_CRW_JS_POST_REQUEST_LOADER_H_
+
+#import <WebKit/WebKit.h>
+
+@class CRWWKScriptMessageRouter;
+
+// Class to load POST requests in a provided web view via JavaScript.
+@interface CRWJSPOSTRequestLoader : NSObject
+
+// Asynchronously loads a POST |request| in provided |webView|.
+// It temporarily installs JavaScript message routers with |messageRouter| to
+// handle HTTP errors. The |completionHandler| is called once the request has
+// been executed. In case of successful request, the passed error is nil.
+// The |completionHandler| must not be null. The |messageRouter| and |webView|
+// must not be nil. The |request| must be a POST request.
+- (void)loadPOSTRequest:(NSURLRequest*)request
+              inWebView:(WKWebView*)webView
+          messageRouter:(CRWWKScriptMessageRouter*)messageRouter
+      completionHandler:(void (^)(NSError*))completionHandler;
+
+@end
+
+#endif  // IOS_WEB_WEB_STATE_JS_CRW_JS_POST_REQUEST_LOADER_H_