Correct iOS build for latest Xcode beta.

ios/web/web_state/ui/crw_ui_simple_web_view_controller.mm

 // Copyright 2014 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_ui_simple_web_view_controller.h"
 
 #include "base/ios/weak_nsobject.h"
 #import "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
 
@@ skipping 54 matching lines @@
 - (id<CRWSimpleWebViewControllerDelegate>)delegate {
   return _delegate.get();
 }
 
 - (void)loadPDFAtFilePath:(NSString*)filePath {
   DCHECK([[NSFileManager defaultManager] fileExistsAtPath:filePath]);
   NSData* data = [NSData dataWithContentsOfFile:filePath];
   [_webView loadData:data
               MIMEType:@"application/pdf"
       textEncodingName:@"utf-8"
-               baseURL:nil];
+               baseURL:[NSURL URLWithString:@""]];
 }
 
 - (void)evaluateJavaScript:(NSString*)script
        stringResultHandler:(web::JavaScriptCompletion)handler {
   web::EvaluateJavaScript(_webView, script, handler);
 }
 
 #pragma mark -
 #pragma mark UIWebViewDelegateMethods
 
@@ skipping 11 matching lines @@
 
 - (void)webViewDidFinishLoad:(UIWebView*)webView {
   if (![_delegate respondsToSelector:@selector(simpleWebViewController:
                                                    titleMayHaveChanged:)]) {
     return;
   }
   [_delegate simpleWebViewController:self titleMayHaveChanged:self.title];
 }
 
 @end