MacViews/a11y: Allow accessibility clients to set new selections in Textfields.

ui/views/controls/textfield/textfield.cc

Index: ui/views/controls/textfield/textfield.cc
diff --git a/ui/views/controls/textfield/textfield.cc b/ui/views/controls/textfield/textfield.cc
index 15df149a4605087f0d292bb23724738a7b3009a5..311928403e8efb801de8be7c649e5645c6540fad 100644
--- a/ui/views/controls/textfield/textfield.cc
+++ b/ui/views/controls/textfield/textfield.cc
@@ -1415,7 +1415,7 @@ bool Textfield::GetSelectionRange(gfx::Range* range) const {
 }
 
 bool Textfield::SetSelectionRange(const gfx::Range& range) {
-  if (!ImeEditingAllowed() || !range.IsValid())
+  if (!enabled() || !range.IsValid())

[tapted, 2017/02/14 05:45:32]

as discussed - I'm not sure about changing this without changing a few other
sites in textfield.cc. And after checking password fields in Cocoa, the right
thing to do might be to make the selected range attribute unmodifiable via a11y
to be consistent (and having the test verify this). But that's fine as a
follow-up with a note in the test that the behaviour is inconsistent with Cocoa
(i.e. NSAccessibilitySelectedTextRangeAttribute shouldn't be settable after
doing SetReadOnly(true).

[Patti Lor, 2017/02/15 06:34:47]

Yep, so as discovered & discussed offline, selection-only NSTextfields allow
setting SelectedTextRange via a11y, but not NSSecureTextfields. I've reverted
this file, and added a note in the test to say that we deviate from Cocoa
behaviour here & filed https://crbug.com/692362.

     return false;
   OnBeforeUserAction();
   SelectRange(range);