[ObjC ARC] Converts ios/chrome/app/application_delegate:test_support to ARC.

ios/chrome/app/application_delegate/mock_tab_opener.mm

Index: ios/chrome/app/application_delegate/mock_tab_opener.mm
diff --git a/ios/chrome/app/application_delegate/mock_tab_opener.mm b/ios/chrome/app/application_delegate/mock_tab_opener.mm
index 1aaf9276464a93e3cea3320e8540a9f533a91a7e..9fde4b80d19ec528ce6f8a011fb320e6460810ee 100644
--- a/ios/chrome/app/application_delegate/mock_tab_opener.mm
+++ b/ios/chrome/app/application_delegate/mock_tab_opener.mm
@@ -10,8 +10,12 @@
 #include "ui/base/page_transition_types.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface MockTabOpener () {
-  base::mac::ScopedBlock<ProceduralBlock> _completionBlock;
+  ProceduralBlock _completionBlock;

[sdefresne, 2017/02/21 09:42:40]

I think you can @synthesize this property now.

[stkhapugin, 2017/02/21 12:53:02]

Done.

 }
 
 @end
@@ -27,7 +31,7 @@
                                    completion:(ProceduralBlock)handler {
   _url = url;
   _applicationMode = targetMode;
-  _completionBlock.reset([handler copy]);
+  _completionBlock = [handler copy];
 }
 
 - (void)resetURL {