[ObjC ARC] Converts ios/chrome/browser/ui:ui_internal_arc to ARC.

ios/chrome/browser/ui/external_file_controller.mm

 // Copyright (c) 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/chrome/browser/ui/external_file_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #include "base/logging.h"
-#import "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #import "ios/chrome/browser/tabs/tab_model.h"
 #import "ios/web/public/web_view_creation_util.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 // The path relative to the <Application_Home>/Documents/ directory where the
 // files received from other applications are saved.
 NSString* const kInboxPath = @"Inbox";
 
 // Conversion factor to turn number of days to number of seconds.
 const CFTimeInterval kSecondsPerDay = 60 * 60 * 24;
 
 }  // namespace
 
 @interface ExternalFileController ()
 // Returns the path to the Inbox directory.
 + (NSString*)inboxDirectoryPath;
 @end
 
 @implementation ExternalFileController {
-  base::scoped_nsobject<WKWebView> _webView;
+  WKWebView* _webView;
 }
 
 - (instancetype)initWithURL:(const GURL&)URL
                browserState:(web::BrowserState*)browserState {
   self = [super initWithURL:URL];
   if (self) {
-    _webView.reset([web::BuildWKWebView(CGRectZero, browserState) retain]);
+    _webView = web::BuildWKWebView(CGRectZero, browserState);
     [_webView setBackgroundColor:[UIColor whiteColor]];
     [_webView setAutoresizingMask:(UIViewAutoresizingFlexibleWidth |
                                    UIViewAutoresizingFlexibleHeight)];
     [_webView setUserInteractionEnabled:YES];
-    base::scoped_nsobject<UIView> view(
-        [[UIView alloc] initWithFrame:CGRectZero]);
+    UIView* view = [[UIView alloc] initWithFrame:CGRectZero];
     self.view = view;
     [self.view addSubview:_webView];
     [self.view setAutoresizingMask:(UIViewAutoresizingFlexibleWidth |
                                     UIViewAutoresizingFlexibleHeight)];
     NSString* filePath = [ExternalFileController pathForExternalFileURL:URL];
     DCHECK([[NSFileManager defaultManager] fileExistsAtPath:filePath]);
     // TODO(cgrigoruta): Currently only PDFs are supported. Change it to support
     // other file types as well.
     NSURL* fileURL = [NSURL fileURLWithPath:filePath];
     DCHECK(fileURL);
@@ skipping 52 matching lines @@
     if (error) {
       DLOG(ERROR) << "Failed to remove file " << filePath << ": "
                   << base::SysNSStringToUTF8([error description]);
       continue;
     }
   }
 }
 
 - (void)dealloc {
   [_webView removeFromSuperview];
-  [super dealloc];
 }
 
 @end