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..7f5ff25168fb5eb6528ac66f7de57c6df1b194a8
--- /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) {
+
+  /**
+   * 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();
+}