Add ScopedObjCClassSwizzler in base/mac, absorbs objc_method_swizzle and ScopedClassSwizzler

chrome/common/mac/objc_method_swizzle_unittest.mm

-// Copyright (c) 2011 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 "chrome/common/mac/objc_method_swizzle.h"
-
-#include "base/mac/scoped_nsobject.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-@interface ObjcMethodSwizzleTest : NSObject
-- (id)self;
-
-- (NSInteger)one;
-- (NSInteger)two;
-@end
-
-@implementation ObjcMethodSwizzleTest : NSObject
-- (id)self {
-  return [super self];
-}
-
-- (NSInteger)one {
-  return 1;
-}
-- (NSInteger)two {
-  return 2;
-}
-@end
-
-@interface ObjcMethodSwizzleTest (ObjcMethodSwizzleTestCategory)
-- (NSUInteger)hash;
-@end
-
-@implementation ObjcMethodSwizzleTest (ObjcMethodSwizzleTestCategory)
-- (NSUInteger)hash {
-  return [super hash];
-}
-@end
-
-namespace ObjcEvilDoers {
-
-TEST(ObjcMethodSwizzleTest, GetImplementedInstanceMethod) {
-  EXPECT_EQ(class_getInstanceMethod([NSObject class], @selector(dealloc)),
-            GetImplementedInstanceMethod([NSObject class], @selector(dealloc)));
-  EXPECT_EQ(class_getInstanceMethod([NSObject class], @selector(self)),
-            GetImplementedInstanceMethod([NSObject class], @selector(self)));
-  EXPECT_EQ(class_getInstanceMethod([NSObject class], @selector(hash)),
-            GetImplementedInstanceMethod([NSObject class], @selector(hash)));
-
-  Class testClass = [ObjcMethodSwizzleTest class];
-  EXPECT_EQ(class_getInstanceMethod(testClass, @selector(self)),
-            GetImplementedInstanceMethod(testClass, @selector(self)));
-  EXPECT_NE(class_getInstanceMethod([NSObject class], @selector(self)),
-            class_getInstanceMethod(testClass, @selector(self)));
-
-  EXPECT_TRUE(class_getInstanceMethod(testClass, @selector(dealloc)));
-  EXPECT_FALSE(GetImplementedInstanceMethod(testClass, @selector(dealloc)));
-}
-
-TEST(ObjcMethodSwizzleTest, SwizzleImplementedInstanceMethods) {
-  base::scoped_nsobject<ObjcMethodSwizzleTest> object(
-      [[ObjcMethodSwizzleTest alloc] init]);
-  EXPECT_EQ([object one], 1);
-  EXPECT_EQ([object two], 2);
-
-  Class testClass = [object class];
-  SwizzleImplementedInstanceMethods(testClass, @selector(one), @selector(two));
-  EXPECT_EQ([object one], 2);
-  EXPECT_EQ([object two], 1);
-
-  SwizzleImplementedInstanceMethods(testClass, @selector(one), @selector(two));
-  EXPECT_EQ([object one], 1);
-  EXPECT_EQ([object two], 2);
-}
-
-}  // namespace ObjcEvilDoers