[ObjC ARC] Converts ios/chrome/test/base:unit_tests to ARC.

ios/chrome/test/base/scoped_block_swizzler_unittest.mm

 // Copyright 2013 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.
 
 #include "base/mac/foundation_util.h"
-#import "base/mac/scoped_nsobject.h"
 #include "ios/chrome/test/base/scoped_block_swizzler.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #import "testing/gtest_mac.h"
 #include "testing/platform_test.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 // Class containing two methods that will be swizzled by the unittests.
 @interface ScopedBlockSwizzlerTestClass : NSObject
 
 // An NSString property that will be accessed by one of the swizzled methods.
 @property(nonatomic, copy) NSString* value;
 
 + (NSString*)classMethodToSwizzle;
 - (NSString*)instanceMethodToSwizzle;
 @end
 
@@ skipping 16 matching lines @@
     EXPECT_NSEQ(kSwizzledClassValue,
                 [ScopedBlockSwizzlerTestClass classMethodToSwizzle]);
   }
 
   EXPECT_NSEQ(kOriginalClassValue,
               [ScopedBlockSwizzlerTestClass classMethodToSwizzle]);
 }
 
 // Tests that swizzling an instance method works properly.
 TEST(ScopedBlockSwizzlerTest, SwizzlingInstanceMethod) {
-  base::scoped_nsobject<ScopedBlockSwizzlerTestClass> target(
-      [[ScopedBlockSwizzlerTestClass alloc] init]);
-  target.get().value = kSwizzledInstanceValue;
+  ScopedBlockSwizzlerTestClass* target =
+      [[ScopedBlockSwizzlerTestClass alloc] init];
+  target.value = kSwizzledInstanceValue;
 
   EXPECT_NSEQ(kOriginalInstanceValue, [target instanceMethodToSwizzle]);
   EXPECT_FALSE([[target instanceMethodToSwizzle]
       isEqualToString:kSwizzledInstanceValue]);
 
   {
     id block = ^NSString*(id self) {
       return base::mac::ObjCCastStrict<ScopedBlockSwizzlerTestClass>(self)
           .value;
     };
@@ skipping 33 matching lines @@
 
 + (NSString*)classMethodToSwizzle {
   return kOriginalClassValue;
 }
 
 - (NSString*)instanceMethodToSwizzle {
   return kOriginalInstanceValue;
 }
 
 @end