Adds a chrome://accessibility page, which:

Adds a toggle for global accessibility mode (on/off)
For each renderer:
- shows an accessibility mode toggle
- if accessibility mode is On, shows a 'Show(/hide) accessibility tree' toggle, which shows(/hides) a text representation of the accessibility tree inline in the page. The accessibility tree may also be refreshed.

BUG=178756

Review URL: https://chromiumcodereview.appspot.com/11791028

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@187417 0039d316-1c4b-4281-b951-d872f2087c98

14 files changed, 604 insertions, 21 deletions

diff --git a/chrome/browser/autocomplete/builtin_provider_unittest.cc b/chrome/browser/autocomplete/builtin_provider_unittest.cc
index 1d71131..0beaf29 100644
--- a/chrome/browser/autocomplete/builtin_provider_unittest.cc
+++ b/chrome/browser/autocomplete/builtin_provider_unittest.cc
@@ -143,8 +143,6 @@ TEST_F(BuiltinProviderTest, ChromeURLs) {
 
   // This makes assumptions about the chrome URLs listed by the BuiltinProvider.
   // Currently they are derived from ChromePaths() in browser_about_handler.cc.
-  const string16 kHostA = ASCIIToUTF16(chrome::kChromeUIAppCacheInternalsHost);
-  const GURL kURLA = GURL(kChrome + kSeparator3 + kHostA);
   const string16 kHostM1 = ASCIIToUTF16(chrome::kChromeUIMediaInternalsHost);
   const string16 kHostM2 = ASCIIToUTF16(chrome::kChromeUIMemoryHost);
   const GURL kURLM1 = GURL(kChrome + kSeparator3 + kHostM1);
@@ -161,23 +159,7 @@ TEST_F(BuiltinProviderTest, ChromeURLs) {
     {kChrome + kSeparator2 + ASCIIToUTF16("host"), 0, {}},
     {kChrome + kSeparator3 + ASCIIToUTF16("host"), 0, {}},
 
-    // Typing an about URL for a unique host should provide that full URL.
-    {kAbout + kSeparator1 + kHostA.substr(0, 1),                   1, {kURLA}},
-    {kAbout + kSeparator2 + kHostA.substr(0, 2),                   1, {kURLA}},
-    {kAbout + kSeparator3 + kHostA.substr(0, kHostA.length() - 1), 1, {kURLA}},
-    {kAbout + kSeparator1 + kHostA,                                1, {kURLA}},
-    {kAbout + kSeparator2 + kHostA,                                1, {kURLA}},
-    {kAbout + kSeparator3 + kHostA,                                1, {kURLA}},
-
-    // Typing a chrome URL for a unique host should provide that full URL.
-    {kChrome + kSeparator1 + kHostA.substr(0, 1),                   1, {kURLA}},
-    {kChrome + kSeparator2 + kHostA.substr(0, 2),                   1, {kURLA}},
-    {kChrome + kSeparator3 + kHostA.substr(0, kHostA.length() - 1), 1, {kURLA}},
-    {kChrome + kSeparator1 + kHostA,                                1, {kURLA}},
-    {kChrome + kSeparator2 + kHostA,                                1, {kURLA}},
-    {kChrome + kSeparator3 + kHostA,                                1, {kURLA}},
-
-    // Typing an about URL with a non-unique host should provide matching URLs.
+    // Typing an about URL should provide matching URLs.
     {kAbout + kSeparator1 + kHostM1.substr(0, 1), 2, {kURLM1, kURLM2}},
     {kAbout + kSeparator2 + kHostM1.substr(0, 2), 2, {kURLM1, kURLM2}},
     {kAbout + kSeparator3 + kHostM1.substr(0, 3), 1, {kURLM1}},
@@ -185,7 +167,7 @@ TEST_F(BuiltinProviderTest, ChromeURLs) {
     {kAbout + kSeparator3 + kHostM1,              1, {kURLM1}},
     {kAbout + kSeparator2 + kHostM2,              1, {kURLM2}},
 
-    // Typing a chrome URL with a non-unique host should provide matching URLs.
+    // Typing a chrome URL should provide matching URLs.
     {kChrome + kSeparator1 + kHostM1.substr(0, 1), 2, {kURLM1, kURLM2}},
     {kChrome + kSeparator2 + kHostM1.substr(0, 2), 2, {kURLM1, kURLM2}},
     {kChrome + kSeparator3 + kHostM1.substr(0, 3), 1, {kURLM1}},
diff --git a/chrome/browser/browser_about_handler.cc b/chrome/browser/browser_about_handler.cc
index dcbd918..b09c624 100644
--- a/chrome/browser/browser_about_handler.cc
+++ b/chrome/browser/browser_about_handler.cc
@@ -21,6 +21,7 @@ namespace {
 // Add paths here to be included in chrome://chrome-urls (about:about).
 // These paths will also be suggested by BuiltinProvider.
 const char* const kPaths[] = {
+  chrome::kChromeUIAccessibilityHost,
   chrome::kChromeUIAppCacheInternalsHost,
   chrome::kChromeUIBlobInternalsHost,
   chrome::kChromeUICacheHost,
diff --git a/content/browser/accessibility/accessibility_ui.cc b/content/browser/accessibility/accessibility_ui.cc
new file mode 100644
index 0000000..9307e9a
--- /dev/null
+++ b/content/browser/accessibility/accessibility_ui.cc
@@ -0,0 +1,282 @@
+// Copyright (c) 2013 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 "content/browser/accessibility/accessibility_ui.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/json/json_writer.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/utf_string_conversions.h"
+#include "base/values.h"
+#include "content/browser/accessibility/accessibility_tree_formatter.h"
+#include "content/browser/accessibility/browser_accessibility_manager.h"
+#include "content/browser/accessibility/browser_accessibility_state_impl.h"
+#include "content/browser/renderer_host/render_widget_host_impl.h"
+#include "content/common/view_message_enums.h"
+#include "content/port/browser/render_widget_host_view_port.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/favicon_status.h"
+#include "content/public/browser/navigation_entry.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_widget_host.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_ui_data_source.h"
+#include "content/public/common/url_constants.h"
+#include "grit/content_resources.h"
+#include "net/base/escape.h"
+
+using base::FundamentalValue;
+using base::ListValue;
+
+static const char kDataFile[] = "targets-data.json";
+
+static const char kProcessIdField[]  = "processId";
+static const char kRouteIdField[]  = "routeId";
+static const char kUrlField[]  = "url";
+static const char kNameField[]  = "name";
+static const char kFaviconUrlField[] = "favicon_url";
+static const char kPidField[]  = "pid";
+static const char kAccessibilityModeField[] = "a11y_mode";
+
+namespace content {
+
+namespace {
+
+DictionaryValue* BuildTargetDescriptor(
+    const GURL& url,
+    const std::string& name,
+    const GURL& favicon_url,
+    int process_id,
+    int route_id,
+    AccessibilityMode accessibility_mode,
+    base::ProcessHandle handle = base::kNullProcessHandle) {
+  DictionaryValue* target_data = new DictionaryValue();
+  target_data->SetInteger(kProcessIdField, process_id);
+  target_data->SetInteger(kRouteIdField, route_id);
+  target_data->SetString(kUrlField, url.spec());
+  target_data->SetString(kNameField, net::EscapeForHTML(name));
+  target_data->SetInteger(kPidField, base::GetProcId(handle));
+  target_data->SetString(kFaviconUrlField, favicon_url.spec());
+  target_data->SetInteger(kAccessibilityModeField,
+                          accessibility_mode);
+  return target_data;
+}
+
+DictionaryValue* BuildTargetDescriptor(RenderViewHost* rvh) {
+  WebContents* web_contents = WebContents::FromRenderViewHost(rvh);
+  std::string title;
+  RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(rvh);
+  AccessibilityMode accessibility_mode = rwhi->accessibility_mode();
+
+  GURL url;
+  GURL favicon_url;
+  if (web_contents) {
+    url = web_contents->GetURL();
+    title = UTF16ToUTF8(web_contents->GetTitle());
+    NavigationController& controller = web_contents->GetController();
+    NavigationEntry* entry = controller.GetActiveEntry();
+    if (entry != NULL && entry->GetURL().is_valid())
+      favicon_url = entry->GetFavicon().url;
+  }
+
+  return BuildTargetDescriptor(url,
+                               title,
+                               favicon_url,
+                               rvh->GetProcess()->GetID(),
+                               rvh->GetRoutingID(),
+                               accessibility_mode);
+}
+
+void SendTargetsData(
+    const WebUIDataSource::GotDataCallback& callback) {
+  scoped_ptr<ListValue> rvh_list(new ListValue());
+
+  for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
+       !it.IsAtEnd(); it.Advance()) {
+    RenderProcessHost* render_process_host = it.GetCurrentValue();
+    DCHECK(render_process_host);
+
+    // Ignore processes that don't have a connection, such as crashed tabs.
+    if (!render_process_host->HasConnection())
+      continue;
+
+    RenderProcessHost::RenderWidgetHostsIterator rwh_it(
+        render_process_host->GetRenderWidgetHostsIterator());
+    for (; !rwh_it.IsAtEnd(); rwh_it.Advance()) {
+      const RenderWidgetHost* rwh = rwh_it.GetCurrentValue();
+      DCHECK(rwh);
+      if (!rwh || !rwh->IsRenderView())
+        continue;
+
+      RenderViewHost* rvh =
+          RenderViewHost::From(const_cast<RenderWidgetHost*>(rwh));
+
+      rvh_list->Append(BuildTargetDescriptor(rvh));
+    }
+  }
+
+  scoped_ptr<DictionaryValue> data(new DictionaryValue());
+  data->Set("list", rvh_list.release());
+  scoped_ptr<FundamentalValue> a11y_mode(new FundamentalValue(
+      BrowserAccessibilityStateImpl::GetInstance()->GetAccessibilityMode()));
+  data->Set("global_a11y_mode", a11y_mode.release());
+
+  std::string json_string;
+  base::JSONWriter::Write(data.get(), &json_string);
+
+  callback.Run(base::RefCountedString::TakeString(&json_string));
+}
+
+bool HandleRequestCallback(
+    const std::string& path,
+    const WebUIDataSource::GotDataCallback& callback) {
+  if (path != kDataFile)
+    return false;
+
+  SendTargetsData(callback);
+  return true;
+}
+
+}  // namespace
+
+AccessibilityUI::AccessibilityUI(WebUI* web_ui)
+  : WebUIController(web_ui) {
+  // Set up the chrome://accessibility source.
+  WebUIDataSource* html_source =
+      WebUIDataSource::Create(chrome::kChromeUIAccessibilityHost);
+  html_source->SetUseJsonJSFormatV2();
+
+  web_ui->RegisterMessageCallback(
+      "toggleAccessibility",
+      base::Bind(&AccessibilityUI::ToggleAccessibility,
+               base::Unretained(this)));
+  web_ui->RegisterMessageCallback(
+      "toggleGlobalAccessibility",
+      base::Bind(&AccessibilityUI::ToggleGlobalAccessibility,
+               base::Unretained(this)));
+  web_ui->RegisterMessageCallback(
+      "requestAccessibilityTree",
+      base::Bind(&AccessibilityUI::RequestAccessibilityTree,
+                 base::Unretained(this)));
+
+  // Add required resources.
+  html_source->SetJsonPath("strings.js");
+  html_source->AddResourcePath("accessibility.css", IDR_ACCESSIBILITY_CSS);
+  html_source->AddResourcePath("accessibility.js", IDR_ACCESSIBILITY_JS);
+  html_source->SetDefaultResource(IDR_ACCESSIBILITY_HTML);
+  html_source->SetRequestFilter(base::Bind(&HandleRequestCallback));
+
+  BrowserContext* browser_context =
+    web_ui->GetWebContents()->GetBrowserContext();
+  WebUIDataSource::Add(browser_context, html_source);
+}
+
+AccessibilityUI::~AccessibilityUI() {
+}
+
+void AccessibilityUI::ToggleAccessibility(const base::ListValue* args) {
+  std::string process_id_str;
+  std::string route_id_str;
+  int process_id;
+  int route_id;
+  CHECK(args->GetSize() == 2);
+  CHECK(args->GetString(0, &process_id_str));
+  CHECK(args->GetString(1, &route_id_str));
+  CHECK(base::StringToInt(process_id_str,
+                          &process_id));
+  CHECK(base::StringToInt(route_id_str, &route_id));
+
+  RenderViewHost* rvh = RenderViewHost::FromID(process_id, route_id);
+  if (!rvh)
+    return;
+  RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(rvh);
+  if (!rwhi)
+    return;
+  AccessibilityMode mode = rwhi->accessibility_mode();
+  if (mode == AccessibilityModeOff)
+    rwhi->SetAccessibilityMode(AccessibilityModeComplete);
+  else
+    rwhi->SetAccessibilityMode(AccessibilityModeOff);
+}
+
+void AccessibilityUI::ToggleGlobalAccessibility(const base::ListValue* args) {
+  BrowserAccessibilityStateImpl* state =
+      BrowserAccessibilityStateImpl::GetInstance();
+  AccessibilityMode mode = state->GetAccessibilityMode();
+  AccessibilityMode new_mode = (mode == AccessibilityModeOff
+                                ? AccessibilityModeComplete
+                                : AccessibilityModeOff);
+  state->SetAccessibilityMode(new_mode);
+  for (RenderProcessHost::iterator it(RenderProcessHost::AllHostsIterator());
+       !it.IsAtEnd(); it.Advance()) {
+    RenderProcessHost* render_process_host = it.GetCurrentValue();
+    DCHECK(render_process_host);
+
+    // Ignore processes that don't have a connection, such as crashed tabs.
+    if (!render_process_host->HasConnection())
+      continue;
+
+    RenderProcessHost::RenderWidgetHostsIterator rwit(
+        render_process_host->GetRenderWidgetHostsIterator());
+    for (; !rwit.IsAtEnd(); rwit.Advance()) {
+      RenderWidgetHost* rwh = const_cast<RenderWidgetHost*>(
+          rwit.GetCurrentValue());
+      DCHECK(rwh);
+      if (!rwh || !rwh->IsRenderView())
+        continue;
+      RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(rwh);
+      rwhi->SetAccessibilityMode(new_mode);
+    }
+  }
+}
+
+void AccessibilityUI::RequestAccessibilityTree(const base::ListValue* args) {
+  std::string process_id_str;
+  std::string route_id_str;
+  int process_id;
+  int route_id;
+  CHECK(args->GetSize() == 2);
+  CHECK(args->GetString(0, &process_id_str));
+  CHECK(args->GetString(1, &route_id_str));
+  CHECK(base::StringToInt(process_id_str, &process_id));
+  CHECK(base::StringToInt(route_id_str, &route_id));
+
+  RenderViewHost* rvh = RenderViewHost::FromID(process_id, route_id);
+  if (!rvh) {
+    scoped_ptr<DictionaryValue> result(new DictionaryValue());
+    result->SetInteger(kProcessIdField, process_id);
+    result->SetInteger(kRouteIdField, route_id);
+    result->Set("error", new StringValue("Renderer no longer exists."));
+    web_ui()->CallJavascriptFunction("accessibility.showTree", *(result.get()));
+    return;
+  }
+
+  scoped_ptr<DictionaryValue> result(BuildTargetDescriptor(rvh));
+  RenderWidgetHostViewPort* host_view = static_cast<RenderWidgetHostViewPort*>(
+      WebContents::FromRenderViewHost(rvh)->GetRenderWidgetHostView());
+  if (!host_view) {
+    result->Set("error", new StringValue("Could not get accessibility tree."));
+    web_ui()->CallJavascriptFunction("accessibility.showTree", *(result.get()));
+    return;
+  }
+  scoped_ptr<AccessibilityTreeFormatter> formatter(
+      AccessibilityTreeFormatter::Create(rvh));
+  string16 accessibility_contents_utf16;
+  BrowserAccessibilityManager* manager =
+      host_view->GetBrowserAccessibilityManager();
+  if (!manager) {
+    result->Set("error", new StringValue("Could not get accessibility tree."));
+    web_ui()->CallJavascriptFunction("accessibility.showTree", *(result.get()));
+    return;
+  }
+  formatter->FormatAccessibilityTree(&accessibility_contents_utf16);
+
+  result->Set("tree",
+              new StringValue(UTF16ToUTF8(accessibility_contents_utf16)));
+  web_ui()->CallJavascriptFunction("accessibility.showTree", *(result.get()));
+}
+
+}  // namespace content
diff --git a/content/browser/accessibility/accessibility_ui.h b/content/browser/accessibility/accessibility_ui.h
new file mode 100644
index 0000000..1b239f8
--- /dev/null
+++ b/content/browser/accessibility/accessibility_ui.h
@@ -0,0 +1,31 @@
+// Copyright (c) 2013 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 CHROME_BROWSER_UI_WEBUI_ACCESSIBILITY_UI_H_
+#define CHROME_BROWSER_UI_WEBUI_ACCESSIBILITY_UI_H_
+
+#include "content/public/browser/web_ui_controller.h"
+
+namespace base {
+  class ListValue;
+}  // namespace base
+
+namespace content {
+
+class AccessibilityUI : public WebUIController {
+ public:
+  explicit AccessibilityUI(WebUI* web_ui);
+  virtual ~AccessibilityUI();
+
+ private:
+  void ToggleAccessibility(const base::ListValue* args);
+  void ToggleGlobalAccessibility(const base::ListValue* args);
+  void RequestAccessibilityTree(const base::ListValue* args);
+
+  DISALLOW_COPY_AND_ASSIGN(AccessibilityUI);
+};
+
+}  // namespace content
+
+#endif  // CHROME_BROWSER_UI_WEBUI_ACCESSIBILITY_UI_H_
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 176784c..716227a 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -148,6 +148,7 @@ RenderWidgetHostImpl::RenderWidgetHostImpl(RenderWidgetHostDelegate* delegate,
       waiting_for_screen_rects_ack_(false),
       mouse_move_pending_(false),
       mouse_wheel_pending_(false),
+      accessibility_mode_(AccessibilityModeOff),
       select_range_pending_(false),
       move_caret_pending_(false),
       needs_repainting_on_restore_(false),
@@ -2217,6 +2218,7 @@ void RenderWidgetHostImpl::SetEditCommandsForNextKeyEvent(
 }
 
 void RenderWidgetHostImpl::SetAccessibilityMode(AccessibilityMode mode) {
+  accessibility_mode_ = mode;
   Send(new ViewMsg_SetAccessibilityMode(routing_id_, mode));
 }
 
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 61d8bfd..9485aa8 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -328,6 +328,11 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   void SetEditCommandsForNextKeyEvent(
       const std::vector<EditCommand>& commands);
 
+  // Gets the accessibility mode.
+  AccessibilityMode accessibility_mode() const {
+    return accessibility_mode_;
+  }
+
   // Send a message to the renderer process to change the accessibility mode.
   void SetAccessibilityMode(AccessibilityMode mode);
 
@@ -738,6 +743,8 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   // would be queued) results in very slow scrolling.
   WheelEventQueue coalesced_mouse_wheel_events_;
 
+  AccessibilityMode accessibility_mode_;
+
   // (Similar to |mouse_move_pending_|.) True while waiting for SelectRange_ACK.
   bool select_range_pending_;
 
diff --git a/content/browser/resources/accessibility/accessibility.css b/content/browser/resources/accessibility/accessibility.css
new file mode 100644
index 0000000..e00a922
--- /dev/null
+++ b/content/browser/resources/accessibility/accessibility.css
@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2013 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.
+ */
+
+body {
+  font-family: Arial, sans-serif;
+  font-size: 12px;
+  margin: 10px;
+  min-width: 47em;
+  padding-bottom: 65px;
+}
+
+img {
+  float: left;
+  height: 16px;
+  padding-right: 5px;
+  width: 16px;
+}
+
+.row {
+  border-bottom: 1px solid #A0A0A0;
+  padding: 5px;
+}
+
+.url {
+  color: #A0A0A0;
+}
+
diff --git a/content/browser/resources/accessibility/accessibility.html b/content/browser/resources/accessibility/accessibility.html
new file mode 100644
index 0000000..c1a2d8d
--- /dev/null
+++ b/content/browser/resources/accessibility/accessibility.html
@@ -0,0 +1,25 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+Copyright (c) 2013 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.
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Accessibility</title>
+  <link rel="stylesheet" href="accessibility.css">
+  <script src="chrome://resources/js/cr.js"></script>
+  <script src="chrome://resources/js/load_time_data.js"></script>
+  <script src="chrome://resources/js/util.js"></script>
+  <script src="strings.js"></script>
+  <script src="accessibility.js"></script>
+</head>
+<body>
+  <h1>Accessibility</h1>
+  <div id="global" class="row">Global accessibility mode:
+    <a id="toggle_global" href="#"></a></div>
+  <div id="pages" class="list"></div>
+  <script src="chrome://resources/js/i18n_template2.js"></script>
+</body>
+</html>
diff --git a/content/browser/resources/accessibility/accessibility.js b/content/browser/resources/accessibility/accessibility.js
new file mode 100644
index 0000000..5d98b48
--- /dev/null
+++ b/content/browser/resources/accessibility/accessibility.js
@@ -0,0 +1,212 @@
+// Copyright (c) 2013 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.
+
+cr.define('accessibility', function() {
+  'use strict';
+
+  function requestData() {
+    var xhr = new XMLHttpRequest();
+    xhr.open('GET', 'targets-data.json', false);
+    xhr.send(null);
+    if (xhr.status === 200) {
+      console.log(xhr.responseText);
+      return JSON.parse(xhr.responseText);
+    }
+    return [];
+  }
+
+  // TODO(aboxhall): add a mechanism to request individual and global a11y
+  // mode, xhr them on toggle... or just re-requestData and be smarter about
+  // ID-ing rows?
+
+  function toggleAccessibility(data, element) {
+    chrome.send('toggleAccessibility',
+                [String(data.processId), String(data.routeId)]);
+    var a11y_was_on = (element.textContent.match(/on/) != null);
+    element.textContent = ' accessibility ' + (a11y_was_on ? ' off' : ' on');
+    var row = element.parentElement;
+    if (a11y_was_on) {
+      while (row.lastChild != element)
+        row.removeChild(row.lastChild);
+    } else {
+      row.appendChild(document.createTextNode(' | '));
+      row.appendChild(createShowAccessibilityTreeElement(data, row, false));
+    }
+  }
+
+  function requestAccessibilityTree(data, element) {
+    chrome.send('requestAccessibilityTree',
+                [String(data.processId), String(data.routeId)]);
+  }
+
+  function toggleGlobalAccessibility() {
+    chrome.send('toggleGlobalAccessibility');
+    document.location.reload(); // FIXME see TODO above
+  }
+
+  function initialize() {
+    console.log('initialize');
+    var data = requestData();
+
+    addGlobalAccessibilityModeToggle(data['global_a11y_mode']);
+
+    $('pages').textContent = '';
+
+    var list = data['list'];
+    for (var i = 0; i < list.length; i++) {
+      addToPagesList(list[i]);
+    }
+  }
+
+  function addGlobalAccessibilityModeToggle(global_a11y_mode) {
+    $('toggle_global').textContent = (global_a11y_mode == 0 ? 'off' : 'on');
+    $('toggle_global').addEventListener('click',
+                                        toggleGlobalAccessibility);
+  }
+
+  function addToPagesList(data) {
+    // TODO: iterate through data and pages rows instead
+    var id = data['processId'] + '.' + data['routeId'];
+    var row = document.createElement('div');
+    row.className = 'row';
+    row.id = id;
+    formatRow(row, data);
+
+    row.processId = data.processId;
+    row.routeId = data.routeId;
+
+    var list = $('pages');
+    list.appendChild(row);
+  }
+
+  function formatRow(row, data) {
+    if (!('url' in data)) {
+      if ('error' in data) {
+        row.appendChild(createErrorMessageElement(data, row));
+        return;
+      }
+    }
+    var properties = ['favicon_url', 'name', 'url'];
+    for (var j = 0; j < properties.length; j++)
+      row.appendChild(formatValue(data, properties[j]));
+
+    row.appendChild(createToggleAccessibilityElement(data));
+    if (data['a11y_mode'] != 0) {
+      row.appendChild(document.createTextNode(' | '));
+      if ('tree' in data) {
+        row.appendChild(createShowAccessibilityTreeElement(data, row, true));
+        row.appendChild(document.createTextNode(' | '));
+        row.appendChild(createHideAccessibilityTreeElement(row.id));
+        row.appendChild(createAccessibilityTreeElement(data));
+      }
+      else {
+        row.appendChild(createShowAccessibilityTreeElement(data, row, false));
+        if ('error' in data)
+          row.appendChild(createErrorMessageElement(data, row));
+      }
+    }
+  }
+
+  function formatValue(data, property) {
+    var value = data[property];
+
+    if (property == 'favicon_url') {
+      var faviconElement = document.createElement('img');
+      if (value)
+        faviconElement.src = value;
+      faviconElement.alt = "";
+      return faviconElement;
+    }
+
+    var text = value ? String(value) : '';
+    if (text.length > 100)
+      text = text.substring(0, 100) + '\u2026';  // ellipsis
+
+    var span = document.createElement('span');
+    span.textContent = ' ' + text + ' ';
+    span.className = property;
+    return span;
+  }
+
+  function createToggleAccessibilityElement(data) {
+    var link = document.createElement('a');
+    link.setAttribute('href', '#');
+    var a11y_mode = data['a11y_mode'];
+    link.textContent = 'accessibility ' + (a11y_mode == 0 ? 'off' : 'on');
+    link.addEventListener('click',
+                          toggleAccessibility.bind(this, data, link));
+    return link;
+  }
+
+  function createShowAccessibilityTreeElement(data, row, opt_refresh) {
+    var link = document.createElement('a');
+    link.setAttribute('href', '#');
+    if (opt_refresh)
+      link.textContent = 'refresh accessibility tree';
+    else
+      link.textContent = 'show accessibility tree';
+    link.id = row.id + ':showTree';
+    link.addEventListener('click',
+                          requestAccessibilityTree.bind(this, data, link));
+    return link;
+  }
+
+  function createHideAccessibilityTreeElement(id) {
+    var link = document.createElement('a');
+    link.setAttribute('href', '#');
+    link.textContent = 'hide accessibility tree';
+    link.addEventListener('click',
+                          function() {
+        $(id + ':showTree').textContent = 'show accessibility tree';
+        var existingTreeElements = $(id).getElementsByTagName('pre');
+        for (var i = 0; i < existingTreeElements.length; i++)
+          $(id).removeChild(existingTreeElements[i]);
+        var row = $(id);
+        while (row.lastChild != $(id + ':showTree'))
+          row.removeChild(row.lastChild);
+    });
+    return link;
+  }
+
+  function createErrorMessageElement(data) {
+    var errorMessageElement = document.createElement('div');
+    var errorMessage = data.error;
+    errorMessageElement.innerHTML = errorMessage + '&nbsp;';
+    var closeLink = document.createElement('a');
+    closeLink.href='#';
+    closeLink.textContent = '[close]';
+    closeLink.addEventListener('click', function() {
+        var parentElement = errorMessageElement.parentElement;
+        parentElement.removeChild(errorMessageElement);
+        if (parentElement.childElementCount == 0)
+          parentElement.parentElement.removeChild(parentElement);
+    });
+    errorMessageElement.appendChild(closeLink);
+    return errorMessageElement;
+  }
+
+  function showTree(data) {
+    var id = data.processId + '.' + data.routeId;
+    var row = $(id);
+    if (!row)
+      return;
+
+    row.textContent = '';
+    formatRow(row, data);
+  }
+
+  function createAccessibilityTreeElement(data) {
+    var treeElement = document.createElement('pre');
+    var tree = data.tree;
+    treeElement.textContent = tree;
+    return treeElement;
+  }
+
+  return {
+    initialize: initialize,
+    showTree: showTree
+  };
+});
+
+document.addEventListener('DOMContentLoaded', accessibility.initialize);
diff --git a/content/browser/webui/content_web_ui_controller_factory.cc b/content/browser/webui/content_web_ui_controller_factory.cc
index 38a5de4..7f486d8 100644
--- a/content/browser/webui/content_web_ui_controller_factory.cc
+++ b/content/browser/webui/content_web_ui_controller_factory.cc
@@ -4,6 +4,7 @@
 
 #include "content/browser/webui/content_web_ui_controller_factory.h"
 
+#include "content/browser/accessibility/accessibility_ui.h"
 #include "content/browser/gpu/gpu_internals_ui.h"
 #include "content/browser/media/media_internals_ui.h"
 #include "content/browser/media/webrtc_internals_ui.h"
@@ -21,7 +22,8 @@ WebUI::TypeID ContentWebUIControllerFactory::GetWebUIType(
       url.host() == chrome::kChromeUITracingHost ||
 #endif
       url.host() == chrome::kChromeUIGpuHost ||
-      url.host() == chrome::kChromeUIMediaInternalsHost) {
+      url.host() == chrome::kChromeUIMediaInternalsHost ||
+      url.host() == chrome::kChromeUIAccessibilityHost) {
     return const_cast<ContentWebUIControllerFactory*>(this);
   }
   return WebUI::kNoWebUI;
@@ -45,6 +47,8 @@ WebUIController* ContentWebUIControllerFactory::CreateWebUIControllerForURL(
     return new GpuInternalsUI(web_ui);
   if (url.host() == chrome::kChromeUIMediaInternalsHost)
     return new MediaInternalsUI(web_ui);
+  if (url.host() == chrome::kChromeUIAccessibilityHost)
+    return new AccessibilityUI(web_ui);
 #if !defined(OS_ANDROID)
   if (url.host() == chrome::kChromeUITracingHost)
     return new TracingUI(web_ui);
diff --git a/content/content_browser.gypi b/content/content_browser.gypi
index 733a0ba..5cf5a91 100644
--- a/content/content_browser.gypi
+++ b/content/content_browser.gypi
@@ -186,6 +186,8 @@
     'browser/accessibility/accessibility_tree_formatter_utils_win.cc',
     'browser/accessibility/accessibility_tree_formatter_utils_win.h',
     'browser/accessibility/accessibility_tree_formatter_win.cc',
+    'browser/accessibility/accessibility_ui.cc',
+    'browser/accessibility/accessibility_ui.h',
     'browser/accessibility/browser_accessibility.cc',
     'browser/accessibility/browser_accessibility.h',
     'browser/accessibility/browser_accessibility_cocoa.h',
diff --git a/content/content_resources.grd b/content/content_resources.grd
index 04ebe89..83b0cb4 100644
--- a/content/content_resources.grd
+++ b/content/content_resources.grd
@@ -11,6 +11,9 @@
   <translations />
   <release seq="1">
     <includes>
+      <include name="IDR_ACCESSIBILITY_HTML" file="browser/resources/accessibility/accessibility.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
+      <include name="IDR_ACCESSIBILITY_CSS" file="browser/resources/accessibility/accessibility.css" type="BINDATA" />
+      <include name="IDR_ACCESSIBILITY_JS" file="browser/resources/accessibility/accessibility.js" flattenhtml="true" type="BINDATA" />
       <include name="IDR_GPU_BLACKLIST" file="browser/gpu/software_rendering_list.json" type="BINDATA" />
       <include name="IDR_GPU_INTERNALS_HTML" file="browser/resources/gpu/gpu_internals.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />
       <include name="IDR_GPU_INTERNALS_JS" file="browser/resources/gpu/gpu_internals.js" flattenhtml="true" type="BINDATA" />
diff --git a/content/public/common/url_constants.cc b/content/public/common/url_constants.cc
index 057545c..40b3b03 100644
--- a/content/public/common/url_constants.cc
+++ b/content/public/common/url_constants.cc
@@ -33,6 +33,7 @@ const char kViewSourceScheme[] = "view-source";
 const char kAboutBlankURL[] = "about:blank";
 const char kAboutSrcDocURL[] = "about:srcdoc";
 const char kChromeUIAppCacheInternalsHost[] = "appcache-internals";
+const char kChromeUIAccessibilityHost[] = "accessibility";
 const char kChromeUIBlobInternalsHost[] = "blob-internals";
 const char kChromeUIBrowserCrashHost[] = "inducebrowsercrashforrealz";
 const char kChromeUIDevToolsHost[] = "devtools";
diff --git a/content/public/common/url_constants.h b/content/public/common/url_constants.h
index ece09e65..ef45d26 100644
--- a/content/public/common/url_constants.h
+++ b/content/public/common/url_constants.h
@@ -39,6 +39,7 @@ CONTENT_EXPORT extern const char kViewSourceScheme[];
 // Hosts for about URLs.
 CONTENT_EXPORT extern const char kAboutBlankURL[];
 CONTENT_EXPORT extern const char kAboutSrcDocURL[];
+CONTENT_EXPORT extern const char kChromeUIAccessibilityHost[];
 CONTENT_EXPORT extern const char kChromeUIAppCacheInternalsHost[];
 CONTENT_EXPORT extern const char kChromeUIBlobInternalsHost[];
 CONTENT_EXPORT extern const char kChromeUIBrowserCrashHost[];