MacViews/a11y: Allow accessibility clients to update the selected text.

ui/accessibility/platform/ax_platform_node_mac.mm

 // Copyright 2014 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.
 
 #import "ui/accessibility/platform/ax_platform_node_mac.h"
 
 #import <Cocoa/Cocoa.h>
 #include <stddef.h>
 
 #include "base/macros.h"
@@ skipping 360 matching lines @@
   if ([attributeName isEqualToString:NSAccessibilitySelectedAttribute] ||
       [attributeName
           isEqualToString:NSAccessibilitySelectedChildrenAttribute] ||
       [attributeName
           isEqualToString:NSAccessibilitySelectedTextRangeAttribute] ||
       [attributeName
           isEqualToString:NSAccessibilityVisibleCharacterRangeAttribute]) {
     return NO;
   }
 
-  if ([attributeName isEqualToString:NSAccessibilityValueAttribute])
+  if ([attributeName isEqualToString:NSAccessibilityValueAttribute] ||
+      [attributeName isEqualToString:NSAccessibilitySelectedTextAttribute])
     return node_->GetDelegate()->CanSetStringValue();
-  // TODO(patricialor): Implement and merge with conditional for value above.
-  if ([attributeName isEqualToString:NSAccessibilitySelectedTextAttribute])
-    return NO;
 
   if ([attributeName isEqualToString:NSAccessibilityFocusedAttribute]) {
     if (ui::AXViewState::IsFlagSet(node_->GetData().state,
                                    ui::AX_STATE_FOCUSABLE))
       return NO;
   }
 
   // TODO(patricialor): Add callbacks for updating the above attributes except
   // NSAccessibilityValueAttribute and return YES.
   return NO;
 }
 
 - (void)accessibilitySetValue:(id)value forAttribute:(NSString*)attribute {
   if ([attribute isEqualToString:NSAccessibilityValueAttribute] &&
       [value isKindOfClass:[NSString class]])

[tapted, 2016/10/20 05:54:59]

perhaps at the top of the function, 

if (![value isKindOfClass:[NSString class]])
  return;

[Patti Lor, 2016/10/24 04:31:48]

This doesn't work for all attributes - e.g., NSAccessibilityFocusAttribute is
normally writable, but will be passed as a NSNumber which wraps a bool value.

[tapted, 2016/10/24 06:11:57]

Acknowledged.

-    node_->GetDelegate()->SetStringValue(base::SysNSStringToUTF16(value));
+    node_->GetDelegate()->SetStringValue(base::SysNSStringToUTF16(value),
+                                         false);

[tapted, 2016/10/20 05:54:59]

now that the body spans 2 lines, the `if` (and else) needs curlies

[Patti Lor, 2016/10/24 04:31:48]

Done.

+  else if ([attribute isEqualToString:NSAccessibilitySelectedTextAttribute] &&
+           [value isKindOfClass:[NSString class]])
+    node_->GetDelegate()->SetStringValue(base::SysNSStringToUTF16(value), true);
 
   // TODO(patricialor): Plumb through all the other writable attributes as
   // specified in accessibilityIsAttributeSettable.
 }
 
 - (id)accessibilityAttributeValue:(NSString*)attribute {
   SEL selector = NSSelectorFromString(attribute);
   if ([self respondsToSelector:selector])
     return [self performSelector:selector];
   return nil;
@@ skipping 170 matching lines @@
   }
   NotifyMacEvent(native_node_, event_type);
 }
 
 int AXPlatformNodeMac::GetIndexInParent() {
   // TODO(dmazzoni): implement this.  http://crbug.com/396137
   return -1;
 }
 
 }  // namespace ui