Implement automatic load of composed/embedded automation trees

chrome/renderer/resources/extensions/automation_custom_bindings.js

 // 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.
 
 // Custom bindings for the automation API.
 var AutomationNode = require('automationNode').AutomationNode;
 var AutomationRootNode = require('automationNode').AutomationRootNode;
 var automation = require('binding').Binding.create('automation');
 var automationInternal =
     require('binding').Binding.create('automationInternal').generate();
 var eventBindings = require('event_bindings');
 var Event = eventBindings.Event;
 var forEach = require('utils').forEach;
 var lastError = require('lastError');
 var logging = requireNative('logging');
 var schema = requireNative('automationInternal').GetSchemaAdditions();
 
+/**
+ * A namespace to export utility functions to other files in automation.
+ */
+window.automationUtil = function() {};

[aboxhall, 2014/11/03 17:15:49]

I'm really not sure about the implications of this. It might be fine, but it
makes me nervous. What is |window| here?

[David Tseng, 2014/11/03 19:31:53]

kalman can probably better comment, but window is the window objet running
within the v8 context for the extension system; I don't think the extension's
background page runs in the same context (i.e. it has a different window
object).

+
 // TODO(aboxhall): Look into using WeakMap
-var idToAutomationRootNode = {};
+automationUtil.idToAutomationRootNode = {};
 var idToCallback = {};
 
-// TODO(dtseng): Move out to automation/automation_util.js or as a static member
-// of AutomationRootNode to keep this file clean.
-/*
- * Creates an id associated with a particular AutomationRootNode based upon a
- * renderer/renderer host pair's process and routing id.
- */
-var createAutomationRootNodeID = function(pid, rid) {
-  return pid + '_' + rid;
+automationUtil.DESKTOP_TREE_ID = 0;

[aboxhall, 2014/11/03 17:15:49]

Why does DESKTOP_TREE_ID need to be on automationUtil? I don't see it used in
automation_node.js.

[David Tseng, 2014/11/03 19:31:53]

Removed.

+
+automationUtil.storeTreeCallback = function(id, callback) {
+  if (!callback)
+    return;
+
+  var targetTree = automationUtil.idToAutomationRootNode[id];
+  if (!targetTree) {
+    // If we haven't cached the tree, hold the callback until the tree is
+    // populated by the initial onAccessibilityEvent call.
+    if (id in idToCallback)
+      idToCallback[id].push(callback);
+    else
+      idToCallback[id] = [callback];
+  } else {
+    callback(targetTree);
+  }
 };
 
-var DESKTOP_TREE_ID = createAutomationRootNodeID(0, 0);
-
 automation.registerCustomHook(function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
 
   // TODO(aboxhall, dtseng): Make this return the speced AutomationRootNode obj.
   apiFunctions.setHandleRequest('getTree', function getTree(tabId, callback) {
     // enableTab() ensures the renderer for the active or specified tab has
-    // accessibility enabled, and fetches its process and routing ids to use as
-    // a key in the idToAutomationRootNode map. The callback to enableTab is is
-    // bound to the callback passed in to getTree(), so that once the tree is
-    // available (either due to having been cached earlier, or after an
-    // accessibility event occurs which causes the tree to be populated), the
+    // accessibility enabled, and fetches its ax tree id to use as
+    // a key in the automationUtil.idToAutomationRootNode map. The callback to
+    // enableTab is bound to the callback passed in to getTree(), so that once
+    // the tree is available (either due to having been cached earlier, or after
+    // an accessibility event occurs which causes the tree to be populated), the
     // callback can be called.
-    automationInternal.enableTab(tabId, function onEnable(pid, rid) {
+    automationInternal.enableTab(tabId, function onEnable(id) {
       if (lastError.hasError(chrome)) {
         callback();
         return;
       }
-      var id = createAutomationRootNodeID(pid, rid);
-      var targetTree = idToAutomationRootNode[id];
-      if (!targetTree) {
-        // If we haven't cached the tree, hold the callback until the tree is
-        // populated by the initial onAccessibilityEvent call.
-        if (id in idToCallback)
-          idToCallback[id].push(callback);
-        else
-          idToCallback[id] = [callback];
-      } else {
-        callback(targetTree);
-      }
+      automationUtil.storeTreeCallback(id, callback);
     });
   });
 
   var desktopTree = null;
   apiFunctions.setHandleRequest('getDesktop', function(callback) {
-    desktopTree = idToAutomationRootNode[DESKTOP_TREE_ID];
+    desktopTree =
+        automationUtil.idToAutomationRootNode[automationUtil.DESKTOP_TREE_ID];
     if (!desktopTree) {
-      if (DESKTOP_TREE_ID in idToCallback)
-        idToCallback[DESKTOP_TREE_ID].push(callback);
+      if (automationUtil.DESKTOP_TREE_ID in idToCallback)
+        idToCallback[automationUtil.DESKTOP_TREE_ID].push(callback);
       else
-        idToCallback[DESKTOP_TREE_ID] = [callback];
+        idToCallback[automationUtil.DESKTOP_TREE_ID] = [callback];
 
       // TODO(dtseng): Disable desktop tree once desktop object goes out of
       // scope.
       automationInternal.enableDesktop(function() {
         if (lastError.hasError(chrome)) {
-          delete idToAutomationRootNode[DESKTOP_TREE_ID];
+          delete automationUtil.idToAutomationRootNode[
+              automationUtil.DESKTOP_TREE_ID];
           callback();
           return;
         }
       });
     } else {
       callback(desktopTree);
     }
   });
 });
 
 // Listen to the automationInternal.onAccessibilityEvent event, which is
 // essentially a proxy for the AccessibilityHostMsg_Events IPC from the
 // renderer.
 automationInternal.onAccessibilityEvent.addListener(function(data) {
-  var pid = data.processID;
-  var rid = data.routingID;
-  var id = createAutomationRootNodeID(pid, rid);
-  var targetTree = idToAutomationRootNode[id];
+  var id = data.treeID;
+  var targetTree = automationUtil.idToAutomationRootNode[id];
   if (!targetTree) {
     // If this is the first time we've gotten data for this tree, it will
     // contain all of the tree's data, so create a new tree which will be
     // bootstrapped from |data|.
-    targetTree = new AutomationRootNode(pid, rid);
-    idToAutomationRootNode[id] = targetTree;
+    targetTree = new AutomationRootNode(id);
+    automationUtil.idToAutomationRootNode[id] = targetTree;
   }
   if (!privates(targetTree).impl.onAccessibilityEvent(data))
     return;
 
   // If we're not waiting on a callback to getTree(), we can early out here.
   if (!(id in idToCallback))
     return;
 
   // We usually get a 'placeholder' tree first, which doesn't have any url
   // attribute or child nodes. If we've got that, wait for the full tree before
   // calling the callback.
   // TODO(dmazzoni): Don't send down placeholder (crbug.com/397553)
-  if (id != DESKTOP_TREE_ID && !targetTree.attributes.url &&
+  if (id != automationUtil.DESKTOP_TREE_ID && !targetTree.attributes.url &&
       targetTree.children.length == 0) {
     return;
   }
 
   // If the tree wasn't available when getTree() was called, the callback will
   // have been cached in idToCallback, so call and delete it now that we
   // have the complete tree.
   for (var i = 0; i < idToCallback[id].length; i++) {
     console.log('calling getTree() callback');
     var callback = idToCallback[id][i];
     callback(targetTree);
   }
   delete idToCallback[id];
 });
 
-automationInternal.onAccessibilityTreeDestroyed.addListener(function(pid, rid) {
-  var id = createAutomationRootNodeID(pid, rid);
-  var targetTree = idToAutomationRootNode[id];
+automationInternal.onAccessibilityTreeDestroyed.addListener(function(id) {
+  var targetTree = automationUtil.idToAutomationRootNode[id];
   if (targetTree) {
     privates(targetTree).impl.destroy();
-    delete idToAutomationRootNode[id];
+    delete automationUtil.idToAutomationRootNode[id];
   } else {
     logging.WARNING('no targetTree to destroy');
   }
-  delete idToAutomationRootNode[id];
+  delete automationUtil.idToAutomationRootNode[id];
 });
 
 exports.binding = automation.generate();
 
 // Add additional accessibility bindings not specified in the automation IDL.
 // Accessibility and automation share some APIs (see
 // ui/accessibility/ax_enums.idl).
 forEach(schema, function(k, v) {
   exports.binding[k] = v;
 });