Refactor content/renderer/accessibility to use AXTreeSerializer (re-land).

This removes the confusing code in content/renderer/accessibility that
serializes updates from Blink's accessibility tree, and replaces it with
calls to the new cleaner and fully-unit-tested AXTreeSerializer class.

BUG=316726

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=261099

Review URL: https://codereview.chromium.org/125763003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261408 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/accessibility/browser_accessibility_manager.cc

@@ -131,7 +131,7 @@ void BrowserAccessibilityManager::OnAccessibilityEvents(
   // Process all changes to the accessibility tree first.
   for (uint32 index = 0; index < params.size(); index++) {
     const AccessibilityHostMsg_EventParams& param = params[index];
-    if (!UpdateNodes(param.nodes))
+    if (!UpdateNodes(param.update.nodes))
       return;
 
     // Set initial focus when a page is loaded.

content/browser/accessibility/browser_accessibility_manager_unittest.cc

@@ -267,8 +267,8 @@ TEST(BrowserAccessibilityManagerTest, TestReuseBrowserAccessibilityObjects) {
   params.push_back(AccessibilityHostMsg_EventParams());
   AccessibilityHostMsg_EventParams* msg = &params[0];
   msg->event_type = ui::AX_EVENT_CHILDREN_CHANGED;
-  msg->nodes.push_back(tree2_root);
-  msg->nodes.push_back(tree2_child0);
+  msg->update.nodes.push_back(tree2_root);
+  msg->update.nodes.push_back(tree2_child0);
   msg->id = tree2_root.id;
   manager->OnAccessibilityEvents(params);
 
@@ -444,9 +444,9 @@ TEST(BrowserAccessibilityManagerTest, TestReuseBrowserAccessibilityObjects2) {
   params.push_back(AccessibilityHostMsg_EventParams());
   AccessibilityHostMsg_EventParams* msg = &params[0];
   msg->event_type = ui::AX_EVENT_CHILDREN_CHANGED;
-  msg->nodes.push_back(tree2_container);
-  msg->nodes.push_back(tree2_child0);
-  msg->nodes.push_back(tree2_grandchild0);
+  msg->update.nodes.push_back(tree2_container);
+  msg->update.nodes.push_back(tree2_child0);
+  msg->update.nodes.push_back(tree2_grandchild0);
   msg->id = tree2_container.id;
   manager->OnAccessibilityEvents(params);
 
@@ -551,10 +551,10 @@ TEST(BrowserAccessibilityManagerTest, TestMoveChildUp) {
   params.push_back(AccessibilityHostMsg_EventParams());
   AccessibilityHostMsg_EventParams* msg = &params[0];
   msg->event_type = ui::AX_EVENT_CHILDREN_CHANGED;
-  msg->nodes.push_back(tree2_1);
-  msg->nodes.push_back(tree2_4);
-  msg->nodes.push_back(tree2_5);
-  msg->nodes.push_back(tree2_6);
+  msg->update.nodes.push_back(tree2_1);
+  msg->update.nodes.push_back(tree2_4);
+  msg->update.nodes.push_back(tree2_5);
+  msg->update.nodes.push_back(tree2_6);
   msg->id = tree2_1.id;
   manager->OnAccessibilityEvents(params);
 

content/browser/accessibility/browser_accessibility_win_unittest.cc

@@ -235,7 +235,7 @@ TEST_F(BrowserAccessibilityTest, TestChildrenChange) {
   text2.SetName("old text");
   AccessibilityHostMsg_EventParams param;
   param.event_type = ui::AX_EVENT_CHILDREN_CHANGED;
-  param.nodes.push_back(text2);
+  param.update.nodes.push_back(text2);
   param.id = text2.id;
   std::vector<AccessibilityHostMsg_EventParams> events;
   events.push_back(param);
@@ -307,7 +307,7 @@ TEST_F(BrowserAccessibilityTest, TestChildrenChangeNoLeaks) {
   root.child_ids.clear();
   AccessibilityHostMsg_EventParams param;
   param.event_type = ui::AX_EVENT_CHILDREN_CHANGED;
-  param.nodes.push_back(root);
+  param.update.nodes.push_back(root);
   param.id = root.id;
   std::vector<AccessibilityHostMsg_EventParams> events;
   events.push_back(param);
@@ -637,8 +637,8 @@ TEST_F(BrowserAccessibilityTest, TestCreateEmptyDocument) {
   params.push_back(AccessibilityHostMsg_EventParams());
   AccessibilityHostMsg_EventParams* msg = &params[0];
   msg->event_type = ui::AX_EVENT_LOAD_COMPLETE;
-  msg->nodes.push_back(tree1_1);
-  msg->nodes.push_back(tree1_2);
+  msg->update.nodes.push_back(tree1_1);
+  msg->update.nodes.push_back(tree1_2);
   msg->id = tree1_1.id;
   manager->OnAccessibilityEvents(params);
 
@@ -662,9 +662,9 @@ TEST_F(BrowserAccessibilityTest, TestCreateEmptyDocument) {
   tree2_2.id = 3;
   tree2_2.role = ui::AX_ROLE_BUTTON;
 
-  msg->nodes.clear();
-  msg->nodes.push_back(tree2_1);
-  msg->nodes.push_back(tree2_2);
+  msg->update.nodes.clear();
+  msg->update.nodes.push_back(tree2_1);
+  msg->update.nodes.push_back(tree2_2);
   msg->id = tree2_1.id;
 
   // Fire another load complete.

content/browser/renderer_host/render_view_host_impl.cc

@@ -1728,7 +1728,7 @@ void RenderViewHostImpl::OnAccessibilityEvents(
     for (unsigned int i = 0; i < params.size(); ++i) {
       const AccessibilityHostMsg_EventParams& param = params[i];
       AXEventNotificationDetails detail(
-          param.nodes, param.event_type, param.id, GetRoutingID());
+          param.update.nodes, param.event_type, param.id, GetRoutingID());
       details.push_back(detail);
     }
 
@@ -1747,12 +1747,10 @@ void RenderViewHostImpl::OnAccessibilityEvents(
     const AccessibilityHostMsg_EventParams& param = params[i];
     if (static_cast<int>(param.event_type) < 0)
       continue;
-    ui::AXTreeUpdate update;
-    update.nodes = param.nodes;
     if (!ax_tree_)
-      ax_tree_.reset(new ui::AXTree(update));
+      ax_tree_.reset(new ui::AXTree(param.update));
     else
-      CHECK(ax_tree_->Unserialize(update)) << ax_tree_->error();
+      CHECK(ax_tree_->Unserialize(param.update)) << ax_tree_->error();
     accessibility_testing_callback_.Run(param.event_type);
   }
 }

content/common/accessibility_messages.h

@@ -15,6 +15,7 @@
 #include "ipc/param_traits_macros.h"
 #include "third_party/WebKit/public/web/WebAXEnums.h"
 #include "ui/accessibility/ax_node_data.h"
+#include "ui/accessibility/ax_tree_update.h"
 
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT CONTENT_EXPORT
@@ -45,10 +46,14 @@ IPC_STRUCT_TRAITS_BEGIN(ui::AXNodeData)
   IPC_STRUCT_TRAITS_MEMBER(child_ids)
 IPC_STRUCT_TRAITS_END()
 
+IPC_STRUCT_TRAITS_BEGIN(ui::AXTreeUpdate)
+  IPC_STRUCT_TRAITS_MEMBER(node_id_to_clear)
+  IPC_STRUCT_TRAITS_MEMBER(nodes)
+IPC_STRUCT_TRAITS_END()
+
 IPC_STRUCT_BEGIN(AccessibilityHostMsg_EventParams)
-  // Vector of nodes in the tree that need to be updated before
-  // sending the event.
-  IPC_STRUCT_MEMBER(std::vector<ui::AXNodeData>, nodes)
+  // The tree update.
+  IPC_STRUCT_MEMBER(ui::AXTreeUpdate, update)
 
   // Type of event.
   IPC_STRUCT_MEMBER(ui::AXEvent, event_type)

content/content_renderer.gypi

@@ -65,10 +65,10 @@
     'public/renderer/video_encode_accelerator.cc',
     'public/renderer/video_encode_accelerator.h',
     'public/renderer/web_preferences.h',
-    'renderer/accessibility/accessibility_node_serializer.cc',
-    'renderer/accessibility/accessibility_node_serializer.h',
     'renderer/accessibility/blink_ax_enum_conversion.cc',
     'renderer/accessibility/blink_ax_enum_conversion.h',
+    'renderer/accessibility/blink_ax_tree_source.cc',
+    'renderer/accessibility/blink_ax_tree_source.h',
     'renderer/accessibility/renderer_accessibility.cc',
     'renderer/accessibility/renderer_accessibility.h',
     'renderer/accessibility/renderer_accessibility_complete.cc',

content/renderer/accessibility/accessibility_node_serializer.h

-// 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.
-
-#ifndef CONTENT_RENDERER_ACCESSIBILITY_ACCESSIBILITY_NODE_SERIALIZER_H_
-#define CONTENT_RENDERER_ACCESSIBILITY_ACCESSIBILITY_NODE_SERIALIZER_H_
-
-#include "third_party/WebKit/public/web/WebAXObject.h"
-#include "ui/accessibility/ax_node_data.h"
-
-namespace content {
-
-void SerializeAccessibilityNode(
-    const blink::WebAXObject& src,
-    ui::AXNodeData* dst);
-
-bool ShouldIncludeChildNode(
-    const blink::WebAXObject& parent,
-    const blink::WebAXObject& child);
-
-}  // namespace content
-
-#endif  // CONTENT_RENDERER_ACCESSIBILITY_ACCESSIBILITY_NODE_SERIALIZER_H_

content/renderer/accessibility/blink_ax_tree_source.h

+// 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.
+
+#ifndef CONTENT_RENDERER_ACCESSIBILITY_BLINK_AX_TREE_SOURCE_H_
+#define CONTENT_RENDERER_ACCESSIBILITY_BLINK_AX_TREE_SOURCE_H_
+
+#include "third_party/WebKit/public/web/WebAXObject.h"
+#include "ui/accessibility/ax_node_data.h"
+#include "ui/accessibility/ax_tree_source.h"
+
+namespace content {
+
+class RenderViewImpl;
+
+class BlinkAXTreeSource
+    : public ui::AXTreeSource<blink::WebAXObject> {
+ public:
+  BlinkAXTreeSource(RenderViewImpl* render_view);
+  virtual ~BlinkAXTreeSource();
+
+  // AXTreeSource implementation.
+  virtual blink::WebAXObject GetRoot() const OVERRIDE;
+  virtual blink::WebAXObject GetFromId(int32 id) const OVERRIDE;
+  virtual int32 GetId(blink::WebAXObject node) const OVERRIDE;
+  virtual void GetChildren(
+      blink::WebAXObject node,
+      std::vector<blink::WebAXObject>* out_children) const OVERRIDE;
+  virtual blink::WebAXObject GetParent(blink::WebAXObject node) const
+      OVERRIDE;
+  virtual void SerializeNode(blink::WebAXObject node,
+                             ui::AXNodeData* out_data) const OVERRIDE;
+  virtual bool IsValid(blink::WebAXObject node) const OVERRIDE;
+  virtual bool IsEqual(blink::WebAXObject node1,
+                       blink::WebAXObject node2) const OVERRIDE;
+  virtual blink::WebAXObject GetNull() const OVERRIDE;
+
+  blink::WebDocument GetMainDocument() const;
+
+ private:
+  RenderViewImpl* render_view_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_ACCESSIBILITY_BLINK_AX_TREE_SOURCE_H_

content/renderer/accessibility/renderer_accessibility_complete.h

@@ -11,10 +11,12 @@
 #include "base/containers/hash_tables.h"
 #include "base/memory/weak_ptr.h"
 #include "content/public/renderer/render_view_observer.h"
+#include "content/renderer/accessibility/blink_ax_tree_source.h"
 #include "content/renderer/accessibility/renderer_accessibility.h"
 #include "third_party/WebKit/public/web/WebAXEnums.h"
 #include "third_party/WebKit/public/web/WebAXObject.h"
 #include "ui/accessibility/ax_node_data.h"
+#include "ui/accessibility/ax_tree_serializer.h"
 
 namespace blink {
 class WebDocument;
@@ -50,20 +52,6 @@ class CONTENT_EXPORT RendererAccessibilityComplete
 
   void HandleAXEvent(const blink::WebAXObject& obj, ui::AXEvent event);
 
-  // In order to keep track of what nodes the browser knows about, we keep a
-  // representation of the browser tree - just IDs and parent/child
-  // relationships.
-  struct CONTENT_EXPORT BrowserTreeNode {
-    BrowserTreeNode();
-    virtual ~BrowserTreeNode();
-    int32 id;
-    gfx::Rect location;
-    BrowserTreeNode* parent;
-    std::vector<BrowserTreeNode*> children;
-  };
-
-  virtual BrowserTreeNode* CreateBrowserTreeNode();
-
  protected:
   // Send queued events from the renderer to the browser.
   void SendPendingAccessibilityEvents();
@@ -74,19 +62,6 @@ class CONTENT_EXPORT RendererAccessibilityComplete
   void SendLocationChanges();
 
  private:
-  // Serialize the given accessibility object |obj| and append it to
-  // |dst|, and then recursively also serialize any *new* children of
-  // |obj|, based on what object ids we know the browser already has.
-  // The set of ids serialized is added to |ids_serialized|, and any
-  // ids previously in that set are not serialized again.
-  void SerializeChangedNodes(const blink::WebAXObject& obj,
-                             std::vector<ui::AXNodeData>* dst,
-                             std::set<int>* ids_serialized);
-
-  // Clear the given node and recursively delete all of its descendants
-  // from the browser tree. (Does not delete |browser_node|).
-  void ClearBrowserTreeNode(BrowserTreeNode* browser_node);
-
   // Handlers for messages from the browser to the renderer.
   void OnDoDefaultAction(int acc_obj_id);
   void OnEventsAck();
@@ -107,13 +82,6 @@ class CONTENT_EXPORT RendererAccessibilityComplete
       const blink::WebAXObject& src,
       ui::AXNodeData* dst);
 
-  // Build a tree of serializable ui::AXNodeData nodes to send to the
-  // browser process, given a WebAXObject node from Blink.
-  // Modifies |dst| in-place, it's assumed to be empty.
-  void BuildAccessibilityTree(const blink::WebAXObject& src,
-                              bool include_children,
-                              ui::AXNodeData* dst);
-
   // So we can queue up tasks to be executed later.
   base::WeakPtrFactory<RendererAccessibilityComplete> weak_factory_;
 
@@ -121,11 +89,14 @@ class CONTENT_EXPORT RendererAccessibilityComplete
   // sent to the browser.
   std::vector<AccessibilityHostMsg_EventParams> pending_events_;
 
-  // Our representation of the browser tree.
-  BrowserTreeNode* browser_root_;
+  // The adapter that exposes Blink's accessibility tree to AXTreeSerializer.
+  BlinkAXTreeSource tree_source_;
+
+  // The serializer that sends accessibility messages to the browser process.
+  ui::AXTreeSerializer<blink::WebAXObject> serializer_;
 
-  // A map from IDs to nodes in the browser tree.
-  base::hash_map<int32, BrowserTreeNode*> browser_id_map_;
+  // Current location of every object, so we can detect when it moves.
+  base::hash_map<int, gfx::Rect> locations_;
 
   // The most recently observed scroll offset of the root document element.
   // TODO(dmazzoni): remove once https://bugs.webkit.org/show_bug.cgi?id=73460

content/renderer/accessibility/renderer_accessibility_focus_only.cc

@@ -97,9 +97,9 @@ void RendererAccessibilityFocusOnly::HandleFocusedNodeChanged(
   // has focus, otherwise the focused node.
   event.id = node_has_focus ? next_id_ : 1;
 
-  event.nodes.resize(2);
-  ui::AXNodeData& root = event.nodes[0];
-  ui::AXNodeData& child = event.nodes[1];
+  event.update.nodes.resize(2);
+  ui::AXNodeData& root = event.update.nodes[0];
+  ui::AXNodeData& child = event.update.nodes[1];
 
   // Always include the root of the tree, the document. It always has id 1.
   root.id = 1;

ui/accessibility/ax_tree_serializer.h

@@ -172,10 +172,13 @@ AXTreeSerializer<AXSourceNode>::~AXTreeSerializer() {
 
 template<typename AXSourceNode>
 void AXTreeSerializer<AXSourceNode>::Reset() {
-  if (client_root_) {
-    DeleteClientSubtree(client_root_);
-    client_root_ = NULL;
-  }
+  if (!client_root_)
+    return;
+
+  DeleteClientSubtree(client_root_);
+  client_id_map_.erase(client_root_->id);
+  delete client_root_;
+  client_root_ = NULL;
 }
 
 template<typename AXSourceNode>
@@ -305,9 +308,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChanges(
       // If there's no LCA, just tell the client to destroy the whole
       // tree and then we'll serialize everything from the new root.
       out_update->node_id_to_clear = client_root_->id;
-      DeleteClientSubtree(client_root_);
-      client_id_map_.erase(client_root_->id);
-      client_root_ = NULL;
+      Reset();
     } else if (need_delete) {
       // Otherwise, if we need to reserialize a subtree, first we need
       // to delete those nodes in our client tree so that
@@ -318,6 +319,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChanges(
       for (size_t i = 0; i < client_lca->children.size(); ++i) {
         client_id_map_.erase(client_lca->children[i]->id);
         DeleteClientSubtree(client_lca->children[i]);
+        delete client_lca->children[i];
       }
       client_lca->children.clear();
     }
@@ -342,6 +344,7 @@ void AXTreeSerializer<AXSourceNode>::DeleteClientSubtree(
   for (size_t i = 0; i < client_node->children.size(); ++i) {
     client_id_map_.erase(client_node->children[i]->id);
     DeleteClientSubtree(client_node->children[i]);
+    delete client_node->children[i];
   }
   client_node->children.clear();
 }
@@ -365,10 +368,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChangedNodes(
   int id = tree_->GetId(node);
   ClientTreeNode* client_node = ClientTreeNodeById(id);
   if (!client_node) {
-    if (client_root_) {
-      client_id_map_.erase(client_root_->id);
-      DeleteClientSubtree(client_root_);
-    }
+    Reset();
     client_root_ = new ClientTreeNode();
     client_node = client_root_;
     client_node->id = id;
@@ -408,6 +408,7 @@ void AXTreeSerializer<AXSourceNode>::SerializeChangedNodes(
     if (new_child_ids.find(old_child_id) == new_child_ids.end()) {
       client_id_map_.erase(old_child_id);
       DeleteClientSubtree(old_child);
+      delete old_child;
     } else {
       client_child_id_map[old_child_id] = old_child;
     }

ui/accessibility/ax_tree_source.h

@@ -20,7 +20,7 @@ namespace ui {
 // an accessibility tree will be sent over an IPC before being
 // consumed.
 template<typename AXNodeSource>
-class AX_EXPORT AXTreeSource {
+class AXTreeSource {
  public:
   virtual ~AXTreeSource() {}