Check page URL origin to determine JavaScript alert titles.

ios/chrome/browser/ui/dialogs/dialog_presenter.h

Index: ios/chrome/browser/ui/dialogs/dialog_presenter.h
diff --git a/ios/chrome/browser/ui/dialogs/dialog_presenter.h b/ios/chrome/browser/ui/dialogs/dialog_presenter.h
index 33d38b8c4bfc9ccda6d6928e8d41ff9cc31d20be..75cbbc7762a4e266dbd9e2d136925396ada55b70 100644
--- a/ios/chrome/browser/ui/dialogs/dialog_presenter.h
+++ b/ios/chrome/browser/ui/dialogs/dialog_presenter.h
@@ -77,9 +77,17 @@ class WebState;
 // view controller.
 - (void)tryToPresent;
 
-// Create an title for the alert base on the URL.
+// Create an title for the alert base on the URL (|pageURL|). Assumes that
+// pageURL is the mainFrameURL. (See
+// localizedTItleForJavaScriptAlertFromPage:mainFrameURL).
 + (NSString*)localizedTitleForJavaScriptAlertFromPage:(const GURL&)pageURL;

[Eugene But (OOO till 7-30), 2017/06/29 01:00:01]

Do we even need this method? It is only used in EG tests, which actually goes
against testing best practices and defines back doors only for tests:

go/unit-test-practices?cl=head#public-apis

[PL, 2017/06/29 20:02:21]

Sure thing! I did think about this, and whether it would be worse to change
tests in three places or keep the old API pointing to the new API.

 
+// Create an title for the alert base on the URL (|pageURL|), and its

[Eugene But (OOO till 7-30), 2017/06/29 01:00:01]

s/Create/Creates

[PL, 2017/06/29 20:02:21]

Arg, done!

+// relationship to the |mainFrameURL| (typically these are identical except for
+// when posting alerts from an embedded iframe).
++ (NSString*)localizedTitleForJavaScriptAlertFromPage:(const GURL&)pageURL

[Eugene But (OOO till 7-30), 2017/06/29 01:00:01]

Do we even need this method in the public interface?

[PL, 2017/06/29 20:02:21]

It's only going to be used by the EGTest, but I think this has to stay so those
tests can run (or have this in an internal header rather than the private one?).

This does seem to break the idea of exposing API to tests only, but this was the
case before this CL.

[Eugene But (OOO till 7-30), 2017/06/29 20:35:10]

Can we just hardcode the title in those tests? A agree that encapsulation
violation was not introduced by this CL, but it's something that should be
relatively easy to fix. If it's hard to fix, then let's leave it as it is.

+                                         mainFrameURL:(const GURL&)mainFrameURL;
+
 @end
 
 @interface DialogPresenter (ExposedForTesting)