MacViews a11y: Allow accessibility clients to set the AXValue on some controls.

ui/views/accessibility/native_view_accessibility.cc

 // Copyright (c) 2013 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.
 
 #include "ui/views/accessibility/native_view_accessibility.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/events/event_utils.h"
@@ skipping 197 matching lines @@
   // Return an error if the view can't set the value.
   ui::AXViewState state;
   view_->GetAccessibleState(&state);
   if (state.set_value_callback.is_null())
     return false;
 
   state.set_value_callback.Run(new_value);
   return true;
 }
 
+bool NativeViewAccessibility::CanSetStringValue() {

[tapted, 2016/08/11 04:23:25]

Can/should this be enforced by ui::AX_STATE_READ_ONLY? (i.e. _in theory_ the
ui::AX_STATE_READ_ONLY flag should be set for all cases *unless* there is a
set_value_callback available to change it, but in reality that might be hard

[Patti Lor, 2016/08/12 01:57:42]

I think that's a good idea - AXViewState is meant to be as much like a struct as
possible, so it doesn't enforce this. I've moved the READ_ONLY checks to here
from accessibilityIsAttributeSettable since this class is cross-platform.

+  ui::AXViewState state;
+  view_->GetAccessibleState(&state);
+  return !state.set_value_callback.is_null();
+}
+
 void NativeViewAccessibility::OnWidgetDestroying(Widget* widget) {
   if (parent_widget_ == widget) {
     parent_widget_->RemoveObserver(this);
     parent_widget_ = nullptr;
   }
 }
 
 void NativeViewAccessibility::SetParentWidget(Widget* parent_widget) {
   if (parent_widget_)
     parent_widget_->RemoveObserver(this);
@@ skipping 30 matching lines @@
               child_widget_platform_node->GetDelegate());
       if (child_widget_view_accessibility->parent_widget() != widget)
         child_widget_view_accessibility->SetParentWidget(widget);
     }
 
     result_child_widgets->push_back(child_widget);
   }
 }
 
 }  // namespace views