[iOS Clean] Ignore compiler warnings for |-performSelector:withObject:|.

ios/clean/chrome/browser/ui/context_menu/context_menu_view_controller.mm

 // Copyright 2017 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/clean/chrome/browser/ui/context_menu/context_menu_view_controller.h"
 
 #include "base/logging.h"
 #import "ios/clean/chrome/browser/ui/context_menu/context_menu_context.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 // Typedef the block parameter for UIAlertAction for readability.
 typedef void (^AlertActionHandler)(UIAlertAction*);
 // Sends |commands| to |dispatcher| using |context| as the menu context.
 void DispatchContextMenuCommands(const std::vector<SEL>& commands,
                                  id dispatcher,
                                  ContextMenuContext* context) {
   DCHECK(dispatcher);
   DCHECK(context);
+// |-performSelector:withObject:| throws a warning in ARC because the compiler
+// doesn't know how to handle the memory management of the returned values.
+// Since all ContextMenuCommands return void, these warning can be ignored
+// here.
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
   for (SEL command : commands) {
-    IMP command_imp = [dispatcher methodForSelector:command];
-    DCHECK(command_imp);
-    command_imp(dispatcher, command, context);
+    [dispatcher performSelector:command withObject:context];
   }
+#pragma clang diagnostic pop
 }
 }
 
 @interface ContextMenuViewController ()
 // The dispatcher passed on initialization.
 @property(nonatomic, readonly, weak) id<ContextMenuCommands> dispatcher;
 // The context passed on initialization.
 @property(nonatomic, strong) ContextMenuContext* context;
 
 // Creates an UIAlertAction for |item| using |style| to manage the action's
@@ skipping 47 matching lines @@
                                style:(UIAlertActionStyle)style {
   DCHECK(item);
   // Create a block that dispatches |item|'s ContextMenuCommands.
   AlertActionHandler handler = ^(UIAlertAction* action) {
     DispatchContextMenuCommands(item.commands, self.dispatcher, self.context);
   };
   return [UIAlertAction actionWithTitle:item.title style:style handler:handler];
 }
 
 @end