[iOS/ARC] Fix a violation of ODR in base::BindBlock under ARC.

base/mac/scoped_nsobject_unittest_arc.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.
 
 #include <vector>
 
 #import <CoreFoundation/CoreFoundation.h>
 
 #include "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
-// This free-function is there to ensure that the object file in not discarded
-// at link time when building with gyp (it is required because targets is built
-// as a static library with gyp and not source set which cause the object file
-// to be discarded if no symbol is used). Remove once gyp support is dropped.
-void ScopedNSObjectUnittestArcLinkerWorkaround() {}
-
 namespace {
 
 template <typename NST>
 CFIndex GetRetainCount(const base::scoped_nsobject<NST>& nst) {
   @autoreleasepool {
     return CFGetRetainCount((__bridge CFTypeRef)nst.get()) - 1;
   }
 }
 
 #if __has_feature(objc_arc_weak)
@@ skipping 95 matching lines @@
   base::scoped_nsobject<id> p2([[NSObject alloc] init]);
   EXPECT_TRUE(o1 != p2);
   EXPECT_FALSE(o1 == p2);
   id o2 = p2.get();
   swap(p1, p2);
   EXPECT_EQ(o2, p1.get());
   EXPECT_EQ(o1, p2.get());
 }
 
 }  // namespace