Convert ios/chrome/commong/block_unittest.mm to ARC.

ios/chrome/common/noarc_block_unittest.mm

Index: ios/chrome/common/noarc_block_unittest.mm
diff --git a/ios/chrome/common/block_unittest.mm b/ios/chrome/common/noarc_block_unittest.mm
similarity index 88%
copy from ios/chrome/common/block_unittest.mm
copy to ios/chrome/common/noarc_block_unittest.mm
index 3ff46f844670e17057d67ea6eefa6be6e3c4a0d6..defab36e70f2e0a0cb829bd4971ca6379cdb8e7a 100644
--- a/ios/chrome/common/block_unittest.mm
+++ b/ios/chrome/common/noarc_block_unittest.mm
@@ -8,11 +8,17 @@
 #include "base/memory/ref_counted.h"
 #include "testing/platform_test.h"
 
+#if defined(__has_feature) && __has_feature(objc_arc)
+#error "This file must not be compiled with ARC."
+#endif
+
 // This test verifies assumptions about the murky world of interaction between
 // C++ objects and blocks. Just to make sure.
 
 namespace {
 
+using NoArcBlockTest = PlatformTest;
+
 class RefCountedObject : public base::RefCounted<RefCountedObject> {
  public:
   RefCountedObject() {}
@@ -37,7 +43,7 @@ class RefCountedObject : public base::RefCounted<RefCountedObject> {
   virtual ~RefCountedObject() {}
 };
 
-TEST_F(PlatformTest, BlockAndCPlusPlus) {
+TEST_F(NoArcBlockTest, BlockAndCPlusPlus) {
   RefCountedObject* object = new RefCountedObject();
   object->AddRef();
   EXPECT_TRUE(object->HasOneRef());
@@ -49,7 +55,7 @@ TEST_F(PlatformTest, BlockAndCPlusPlus) {
   }
   EXPECT_TRUE(object->HasOneRef());
 
-  void (^heap_block)(int) = 0;
+  void (^heap_block)(int) = nil;
   {
     scoped_refptr<RefCountedObject> object_ptr(object);
     EXPECT_EQ(2, object->refcount());
@@ -74,8 +80,8 @@ TEST_F(PlatformTest, BlockAndCPlusPlus) {
   object->Release();
 }
 
-TEST_F(PlatformTest, BlockAndVectors) {
-  void (^heap_block)(void) = 0;
+TEST_F(NoArcBlockTest, BlockAndVectors) {
+  void (^heap_block)(void) = nil;
   {
     std::vector<int> vector;
     vector.push_back(0);