Disallow JS execution on WebUI pages.

ios/web/web_state/ui/crw_web_controller.mm

 // Copyright 2012 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.
 
 #import "ios/web/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 2278 matching lines @@
   // |[_webView executeJavaScript:completionHandler:]| is not used here because
   // it does not check that page is the same.
   [self executeJavaScript:script completionHandler:nil];
   [_injectedScriptManagers addObject:JSInjectionManagerClass];
 }
 
 #pragma mark -
 
 - (void)executeUserJavaScript:(NSString*)script
             completionHandler:(web::JavaScriptResultBlock)completion {
+  // For security reasons executing JavaScript on pages with app-specific URLs

[lpromero, 2017/03/23 12:43:48]

Nit: Add a comma after "reasons".

[Eugene But (OOO till 7-30), 2017/03/23 17:45:08]

Done.

+  // is not allowed, because those pages may have elevated privileges.
+  GURL lastCommittedURL = self.webState->GetLastCommittedURL();
+  if (web::GetWebClient()->IsAppSpecificURL(lastCommittedURL)) {
+    if (completion) {
+      dispatch_async(dispatch_get_main_queue(), ^{
+        base::scoped_nsobject<NSError> error([[NSError alloc]
+            initWithDomain:web::kJSEvaluationErrorDomain
+                      code:web::JS_EVALUATION_ERROR_CODE_NO_WEB_VIEW
+                  userInfo:nil]);
+        completion(nil, error);
+      });
+    }
+    return;
+  }
+
   [self setUserInteractionRegistered:YES];
   [self executeJavaScript:script completionHandler:completion];
 }
 
 - (BOOL)respondToMessage:(base::DictionaryValue*)message
        userIsInteracting:(BOOL)userIsInteracting
                originURL:(const GURL&)originURL {
   std::string command;
   if (!message->GetString("command", &command)) {
     DLOG(WARNING) << "JS message parameter not found: command";
@@ skipping 2766 matching lines @@
 - (void)simulateLoadRequestWithURL:(const GURL&)URL {
   _lastRegisteredRequestURL = URL;
   _loadPhase = web::LOAD_REQUESTED;
 }
 
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:kReferrerHeaderName];
 }
 
 @end