Keep track of accessibility focus across windows.

content/browser/accessibility/browser_accessibility_cocoa.mm

 // Copyright (c) 2012 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 <execinfo.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
 
@@ skipping 657 matching lines @@
 }
 
 - (NSNumber*)expanded {
   return [NSNumber numberWithBool:
       GetState(browserAccessibility_, ui::AX_STATE_EXPANDED)];
 }
 
 - (NSNumber*)focused {
   BrowserAccessibilityManager* manager = browserAccessibility_->manager();
   NSNumber* ret = [NSNumber numberWithBool:
-      manager->GetFocus(NULL) == browserAccessibility_];
+      manager->GetFocus() == browserAccessibility_];
   return ret;
 }
 
 - (NSNumber*)grabbed {
   std::string grabbed;
   if (browserAccessibility_->GetHtmlAttribute("aria-grabbed", &grabbed) &&
       grabbed == "true")
     return [NSNumber numberWithBool:YES];
 
   return [NSNumber numberWithBool:NO];
@@ skipping 436 matching lines @@
         [ret addObject:rowElement->ToBrowserAccessibilityCocoa()];
     }
   }
 
   return ret;
 }
 
 - (NSArray*)selectedChildren {
   NSMutableArray* ret = [[[NSMutableArray alloc] init] autorelease];
   BrowserAccessibilityManager* manager = browserAccessibility_->manager();
-  BrowserAccessibility* focusedChild = manager->GetFocus(browserAccessibility_);
+  BrowserAccessibility* focusedChild = manager->GetFocus();
+  if (!focusedChild->IsDescendantOf(browserAccessibility_))
+    focusedChild = nullptr;
 
   // If it's not multiselectable, try to skip iterating over the
   // children.
   if (!GetState(browserAccessibility_, ui::AX_STATE_MULTISELECTABLE)) {
     // First try the focused child.
     if (focusedChild && focusedChild != browserAccessibility_) {
       [ret addObject:focusedChild->ToBrowserAccessibilityCocoa()];
       return ret;
     }
 
@@ skipping 879 matching lines @@
 // Sets the value for an accessibility attribute via the accessibility API.
 - (void)accessibilitySetValue:(id)value forAttribute:(NSString*)attribute {
   if (!browserAccessibility_)
     return;
 
   if ([attribute isEqualToString:NSAccessibilityFocusedAttribute]) {
     BrowserAccessibilityManager* manager = browserAccessibility_->manager();
     NSNumber* focusedNumber = value;
     BOOL focused = [focusedNumber intValue];
     if (focused)
-      manager->SetFocus(browserAccessibility_, true);
+      manager->SetFocus(*browserAccessibility_);

[David Tseng, 2016/01/28 02:00:56]

Btw, how does someone clear focus and is browserAccessibility_ guaranteed to be
non-null?

[dmazzoni, 2016/01/30 00:02:41]

Yes, browserAccessibility_ is non-null because BrowserAccessibilityCocoa
outlives the object it wraps.

What should clear focus mean, now that we're thinking about focus more globally?
Is there a specific use-case?

   }
   if ([attribute isEqualToString:NSAccessibilitySelectedTextRangeAttribute]) {
     NSRange range = [(NSValue*)value rangeValue];
     [self delegate]->AccessibilitySetSelection(
         browserAccessibility_->GetId(), range.location,
         browserAccessibility_->GetId(), range.location + range.length);
   }
 }
 
 // Returns the deepest accessibility child that should not be ignored.
@@ skipping 36 matching lines @@
   if (!browserAccessibility_)
     return [super hash];
   return browserAccessibility_->GetId();
 }
 
 - (BOOL)accessibilityShouldUseUniqueId {
   return YES;
 }
 
 @end