Expose media controls to accessibility

chrome/renderer/resources/extensions/automation_custom_bindings.js

Index: chrome/renderer/resources/extensions/automation_custom_bindings.js
diff --git a/chrome/renderer/resources/extensions/automation_custom_bindings.js b/chrome/renderer/resources/extensions/automation_custom_bindings.js
index 53222ab0cfba6779c2a41cc2905f451c77d67ed3..15415a91e00f423eb542c708503f5ea4f2e6dc0e 100644
--- a/chrome/renderer/resources/extensions/automation_custom_bindings.js
+++ b/chrome/renderer/resources/extensions/automation_custom_bindings.js
@@ -278,16 +278,20 @@ automationInternal.onAccessibilityEvent.addListener(function(eventParams) {
   var id = eventParams.treeID;
   var targetTree = AutomationRootNode.getOrCreate(id);
 
-  // Work around an issue where Chrome sends us 'blur' events on the
-  // root node when nothing has focus, we need to treat those as focus
-  // events but otherwise not handle blur events specially.
   var isFocusEvent = false;
   if (eventParams.eventType == schema.EventType.focus) {
     isFocusEvent = true;
   } else if (eventParams.eventType == schema.EventType.blur) {
+    // Work around an issue where Chrome sends us 'blur' events on the
+    // root node when nothing has focus, we need to treat those as focus
+    // events but otherwise not handle blur events specially.
     var node = privates(targetTree).impl.get(eventParams.targetID);
     if (node == node.root)
       isFocusEvent = true;
+  } else if (eventParams.eventType == schema.EventType.mediaStartedPlaying ||
+      eventParams.eventType == schema.EventType.mediaStoppedPlaying) {
+    // These events are global to the tree.
+    eventParams.targetID = privates(targetTree).impl.id;
   }
 
   // When we get a focus event, ignore the actual event target, and instead