[ObjC ARC] Converts ios/chrome/test/earl_grey:test_support to ARC.

ios/chrome/test/earl_grey/chrome_earl_grey.h

Index: ios/chrome/test/earl_grey/chrome_earl_grey.h
diff --git a/ios/chrome/test/earl_grey/chrome_earl_grey.h b/ios/chrome/test/earl_grey/chrome_earl_grey.h
index f9ac0224b624cdb2a4b96fbe157b217a2942af9f..fdacda6a3c82f946abf28075e151b62ef11997fa 100644
--- a/ios/chrome/test/earl_grey/chrome_earl_grey.h
+++ b/ios/chrome/test/earl_grey/chrome_earl_grey.h
@@ -17,7 +17,10 @@ namespace chrome_test_util {
 // error resulting from the execution, if one occurs. The return value is the
 // result of the JavaScript execution. If the request is timed out, then nil is
 // returned.
-id ExecuteJavaScript(NSString* javascript, NSError** out_error);
+// TODO(crbug.com/690057): Remove __unsafe_unretained once all callers are
+// converted to ARC.
+id ExecuteJavaScript(NSString* javascript,

[sdefresne, 2017/02/09 13:12:17]

I think we'll need to keep the __unsafe_unretained even when all callers are
converted to ARC. I'm not sure, but I think there is no automatic retain
semantic for pointer to pointer in Objective-C and you always need an explicit
annotation with ARC in that case (it may be changed to __autoreleasing then
though).

[lody, 2017/02/09 13:25:44]

It actually seems (
https://clang.llvm.org/docs/AutomaticReferenceCounting.html#template-arguments )
that __autoreleasing is the default in this case, so should be removeable.

[sdefresne, 2017/02/09 13:49:23]

Thank you for the pointer (though I think you meant to link to
https://clang.llvm.org/docs/AutomaticReferenceCounting.html#indirect-parameters).
Good to know.

+                     NSError* __unsafe_unretained* out_error);
 
 }  // namespace chrome_test_util