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

ios/chrome/test/earl_grey/chrome_earl_grey.h

 // Copyright 2016 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.
 
 #ifndef IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_H_
 #define IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_H_
 
 #import <EarlGrey/EarlGrey.h>
 
 #include "url/gurl.h"
 
 namespace chrome_test_util {
 
 // TODO(crbug.com/638674): Evaluate if this can move to shared code.
 // Execute |javascript| on current web state, and wait for either the completion
 // of execution or timeout. If |out_error| is not nil, it is set to the
 // 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
 
 // Test methods that perform actions on Chrome. These methods may read or alter
 // Chrome's internal state programmatically or via the UI, but in both cases
 // will properly synchronize the UI for Earl Grey tests.
 @interface ChromeEarlGrey : NSObject
 
 #pragma mark - History Utilities
 
 // Clears browsing history.
 + (void)clearBrowsingHistory;
 
 #pragma mark - Navigation Utilities
 
 // Loads |URL| in the current WebState with transition of type
 // ui::PAGE_TRANSITION_TYPED, and waits for the page to complete loading, or
 // a timeout.
 + (void)loadURL:(GURL)URL;
 
 // Waits for the page to finish loading or a timeout.
 + (void)waitForPageToFinishLoading;
 
 // Taps html element with |elementID| in the current web view.
 + (void)tapWebViewElementWithID:(NSString*)elementID;
 
 @end
 
 #endif  // IOS_CHROME_TEST_EARL_GREY_CHROME_EARL_GREY_H_