Modifies BlockCleanupTest so that it can be used from ARC code.

Since ARC code cannot refer to NSAutoreleasePool directly, before this
change block_cleanup_test.h cannot be included from ARC-enabled code.
With this change, the header lists block_cleanup_pool_ as id, which
allows such includes.

BUG=None

Review-Url: https://codereview.chromium.org/2623233002
Cr-Commit-Position: refs/heads/master@{#442927}

ios/chrome/test/block_cleanup_test.h

@@ -22,7 +22,7 @@ class BlockCleanupTest : public PlatformTest {
   void SpinRunLoop(NSTimeInterval cleanup_time);
 
  private:
-  NSAutoreleasePool* block_cleanup_pool_;
+  id block_cleanup_pool_;
 };
 
 #endif  // IOS_CHROME_TEST_BLOCK_CLEANUP_TEST_H_

ios/chrome/test/block_cleanup_test.mm

@@ -8,6 +8,7 @@
 
 #include "base/logging.h"
 #import "base/mac/scoped_nsobject.h"
+#import "base/mac/foundation_util.h"
 
 void BlockCleanupTest::SetUp() {
   block_cleanup_pool_ = [[NSAutoreleasePool alloc] init];
@@ -22,7 +23,7 @@ void BlockCleanupTest::TearDown() {
   // Drain the autorelease pool to finish cleaning up after blocks.
   // TODO(rohitrao): Can this be an EXPECT, so as to not crash the whole suite?
   DCHECK(block_cleanup_pool_);
-  [block_cleanup_pool_ release];
+  [base::mac::ObjCCastStrict<NSAutoreleasePool>(block_cleanup_pool_) release];
   block_cleanup_pool_ = nil;
 
   PlatformTest::TearDown();