Adds support for POST request with bodies on WKWebView.

ios/web/web_state/js/resources/post_request.js

Index: ios/web/web_state/js/resources/post_request.js
diff --git a/ios/web/web_state/js/resources/post_request.js b/ios/web/web_state/js/resources/post_request.js
new file mode 100644
index 0000000000000000000000000000000000000000..f7dace5bff2430ec12e00e612451a76767292ac0
--- /dev/null
+++ b/ios/web/web_state/js/resources/post_request.js
@@ -0,0 +1,84 @@
+// 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.
+
+// Provides a way to implement POST requests via XMLHttpRequest.
+// Works around https://bugs.webkit.org/show_bug.cgi?id=145410 on WKWebView.
+
+'use strict';
+
+goog.provide('__crPostRequestWorkaround');
+
+/**
+ * Namespace for this file.
+ */
+__crPostRequestWorkaround = {};
+
+/**
+ * Executes a POST request with given parameters and replaces document body with
+ * the response.
+ * @param {string} url The url of the request.
+ * @param {Object<string,string>} headers Request headers to include in POST.
+ * Each header value must be expressed as a key-value pair in this object.
+ * @param {string} body Request body encoded with Base64.
+ * @param {string} contentType Content-Type header value.
+ */
+__crPostRequestWorkaround.runPostRequest = function(url, headers, body,
+  contentType) {

[noyau (Ping after 24h), 2015/12/04 12:19:18]

Formatting is weird here.

[stkhapugin, 2015/12/04 16:28:10]

Reformatted as per JS style guide: 
// Arguments start on a new line, indented four spaces. Preferred when the
// arguments don't fit on the same line with the function name (or the keyword
// "function") but fit entirely on the second line. Works with very long
// function names, survives renaming without reindenting, low on space.

+
+    /**

[noyau (Ping after 24h), 2015/12/04 12:19:18]

Indent should be 2 here, not 4

[stkhapugin, 2015/12/04 16:28:10]

Done.

+     * Converts a Base64-encoded string to a blob.
+     * @param {string} byteCharacters Base64-encoded data string.
+     * @param {string} contentType Corresponding content type.
+     * @return {Blob} Binary representation of byteCharacters.
+     */
+    var base64ToBlob = function(byteCharacters, contentType) {
+      contentType = contentType || '';
+      var sliceSize = 512;
+      var byteArrays = [];
+      var byteCount = byteCharacters.length;
+      for (var offset = 0; offset < byteCount; offset += sliceSize) {
+        var slice = byteCharacters.slice(offset, offset + sliceSize);
+        var byteNumbers = new Array(slice.length);
+        for (var i = 0; i < slice.length; i++) {
+          byteNumbers[i] = slice.charCodeAt(i);
+        }
+        var byteArray = new Uint8Array(byteNumbers);
+        byteArrays.push(byteArray);
+      }
+      return new Blob(byteArrays, {type: contentType});
+    }
+
+    /**
+    * Creates and executes a POST request.
+    * @param {string} url The url of the request.
+    * @param {Object<string,string>} headers Request headers to include in POST.
+    * Each header value must be expressed as a key-value pair in this object.
+    * @param {string} body Request body encoded with Base64.
+    * @param {string} contentType Content-Type header value.
+    */
+    var createAndSendPostRequest = function(url, headers, body, contentType) {
+      var request = new XMLHttpRequest();
+      request.open('POST', url, false);
+      for (var key in headers) {
+        if (headers.hasOwnProperty(key)) {
+          request.setRequestHeader(key, headers[key]);
+        }
+      }
+      var blob = base64ToBlob(atob(body), contentType);
+      request.send(blob);
+      if (request.status != 200) {
+        throw request.status;
+      }
+      return request.responseText;
+    }
+
+    document.open();
+    try {
+      document.write(createAndSendPostRequest(url, headers, body, contentType));
+      window.webkit.messageHandlers.POSTSuccessHandler.postMessage("");
+    } catch(error) {
+      window.webkit.messageHandlers.POSTErrorHandler.postMessage(error);
+    }
+      document.close();

[noyau (Ping after 24h), 2015/12/04 12:19:18]

Indent is wrong here.

[stkhapugin, 2015/12/04 16:28:10]

Done.

+    }