Reland of [ObjC ARC] Converts ios/chrome/browser/ui/contextual_search:contextual_search to ARC.

ios/chrome/browser/ui/contextual_search/touch_to_search_permissions_mediator.mm

 // Copyright 2016 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/contextual_search/touch_to_search_permissions_mediator.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/command_line.h"
-#import "base/ios/weak_nsobject.h"
 #include "base/logging.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "components/prefs/pref_service.h"
 #include "components/search_engines/template_url_service.h"
 #include "ios/chrome/app/tests_hook.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/chrome_switches.h"
 #include "ios/chrome/browser/pref_names.h"
 #import "ios/chrome/browser/prefs/pref_observer_bridge.h"
 #include "ios/chrome/browser/search_engines/template_url_service_factory.h"
 #include "ios/chrome/browser/sync/sync_setup_service.h"
 #include "ios/chrome/browser/sync/sync_setup_service_factory.h"
 #include "net/base/network_change_notifier.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // Maps pref string values to state enum.
 const struct {
   const char* value;
   TouchToSearch::TouchToSearchPreferenceState state;
 } valueStateMappings[] = {
     {"false", TouchToSearch::DISABLED},
     {"true", TouchToSearch::ENABLED},
     {"", TouchToSearch::UNDECIDED},
 };
 }  // namespace
 
 @interface TouchToSearchPermissionsMediator ()<PrefObserverDelegate> {
   ios::ChromeBrowserState* _browserState;
   SyncSetupService* _syncService;
-  base::WeakNSProtocol<NSObject<TouchToSearchPermissionsChangeAudience>*>
-      _audience;
+  __weak NSObject<TouchToSearchPermissionsChangeAudience>* _audience;
   // Pref observer to track changes to the touch-to-search and search engine
   // prefs.
   std::unique_ptr<PrefObserverBridge> _prefObserverBridge;
 
   // Registrar for pref changes notifications.
   PrefChangeRegistrar _prefChangeRegistrar;
 }
 
 // YES if notifications are being observed.
 @property(nonatomic, assign) BOOL observing;
@@ skipping 30 matching lines @@
     return !tests_hook::DisableContextualSearch();
   }
 
   return NO;
 }
 
 - (instancetype)initWithBrowserState:(ios::ChromeBrowserState*)browserState {
   if ((self = [super init])) {
     if (browserState && browserState->IsOffTheRecord()) {
       // Discard the allocated object and return a nil object.
-      [self release];
       return nil;
     }
     [self setUpBrowserState:browserState];
   }
   return self;
 }
 
 - (instancetype)init {
   NOTREACHED();
   return nil;
 }
 
 - (void)dealloc {
   // Set audience to nil to stop observation.
   self.audience = nil;
-  [super dealloc];
 }
 
 - (void)setUpBrowserState:(ios::ChromeBrowserState*)browserState {
   DCHECK(browserState);
   _browserState = browserState;
   _syncService = SyncSetupServiceFactory::GetForBrowserState(_browserState);
 }
 
 #pragma mark - Property implementation
 
@@ skipping 20 matching lines @@
   NOTREACHED() << "Unexpected preference state (" << state << ")";
 }
 
 - (NSObject<TouchToSearchPermissionsChangeAudience>*)audience {
   return _audience;
 }
 
 - (void)setAudience:
     (NSObject<TouchToSearchPermissionsChangeAudience>*)audience {
   [self stopObserving];
-  _audience.reset(audience);
+  _audience = audience;
   [self startObserving];
 }
 
 #pragma mark - Public methods
 
 - (BOOL)canEnable {
   if (![[self class] isTouchToSearchAvailableOnDevice]) {
     return NO;
   } else if (self.preferenceState == TouchToSearch::DISABLED) {
     return NO;
@@ skipping 103 matching lines @@
           respondsToSelector:@selector(
                                  touchToSearchDidChangePreferenceState:)]) {
     [self.audience touchToSearchDidChangePreferenceState:self.preferenceState];
   }
 }
 
 - (void)maybeNotifyAudienceAsynchronously {
   if (self.audience) {
     if ([self.audience
             respondsToSelector:@selector(touchToSearchPermissionsUpdated)]) {
-      base::WeakNSProtocol<NSObject<TouchToSearchPermissionsChangeAudience>*>
-          audience(self.audience);
+      __weak NSObject<TouchToSearchPermissionsChangeAudience>* audience =
+          self.audience;
       dispatch_async(dispatch_get_main_queue(), ^{
         [audience touchToSearchPermissionsUpdated];
       });
     }
   } else {
     // If audience is now nil, stop observing.
     [self stopObserving];
   }
 }
 
@@ skipping 13 matching lines @@
 
 #pragma mark Notification Center handler
 
 - (void)statusMayHaveChangedWithNotification:(NSNotification*)notification {
   // VoiceOver may have been enabled or disabled, so (if there is an audience
   // object), notify it asynchronously.
   [self maybeNotifyAudienceAsynchronously];
 }
 
 @end