Add an accessibility API for events raised outside of the web content.

BUG=none
TEST=none
patch by Dominic Mazzoni <dmazzoni [at] google>
review url: http://codereview.chromium.org/402099/show


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@37597 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 382 insertions, 0 deletions

diff --git a/chrome/browser/extensions/extension_accessibility_api.cc b/chrome/browser/extensions/extension_accessibility_api.cc
new file mode 100644
index 0000000..24428af
--- /dev/null
+++ b/chrome/browser/extensions/extension_accessibility_api.cc
@@ -0,0 +1,181 @@
+// Copyright (c) 2010 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 "chrome/browser/extensions/extension_tabs_module.h"
+
+#include "base/json/json_writer.h"
+#include "base/string_util.h"
+#include "base/values.h"
+#include "chrome/browser/browser.h"
+#include "chrome/browser/browser_list.h"
+#include "chrome/browser/browser_window.h"
+#include "chrome/browser/extensions/extension_accessibility_api.h"
+#include "chrome/browser/extensions/extension_accessibility_api_constants.h"
+#include "chrome/browser/extensions/extension_function_dispatcher.h"
+#include "chrome/browser/extensions/extension_message_service.h"
+#include "chrome/browser/extensions/extensions_service.h"
+#include "chrome/browser/profile.h"
+#include "chrome/common/extensions/extension.h"
+
+namespace keys = extension_accessibility_api_constants;
+
+// Returns the AccessibilityControlInfo serialized into a JSON string,
+// consisting of an array of a single object of type AccessibilityObject,
+// as defined in the accessibility extension api's json schema.
+std::string ControlInfoToJsonString(const AccessibilityControlInfo* info) {
+  ListValue args;
+  DictionaryValue* dict = new DictionaryValue();
+  info->SerializeToDict(dict);
+  args.Append(dict);
+  std::string json_args;
+  base::JSONWriter::Write(&args, false, &json_args);
+  return json_args;
+}
+
+ExtensionAccessibilityEventRouter*
+    ExtensionAccessibilityEventRouter::GetInstance() {
+  return Singleton<ExtensionAccessibilityEventRouter>::get();
+}
+
+void ExtensionAccessibilityEventRouter::ObserveProfile(Profile* profile) {
+  last_focused_control_dict_.Clear();
+
+  if (registrar_.IsEmpty()) {
+    registrar_.Add(this,
+                   NotificationType::ACCESSIBILITY_WINDOW_OPENED,
+                   NotificationService::AllSources());
+    registrar_.Add(this,
+                   NotificationType::ACCESSIBILITY_WINDOW_CLOSED,
+                   NotificationService::AllSources());
+    registrar_.Add(this,
+                   NotificationType::ACCESSIBILITY_CONTROL_FOCUSED,
+                   NotificationService::AllSources());
+    registrar_.Add(this,
+                   NotificationType::ACCESSIBILITY_CONTROL_ACTION,
+                   NotificationService::AllSources());
+    registrar_.Add(this,
+                   NotificationType::ACCESSIBILITY_TEXT_CHANGED,
+                   NotificationService::AllSources());
+  }
+}
+
+void ExtensionAccessibilityEventRouter::Observe(
+    NotificationType type,
+    const NotificationSource& source,
+    const NotificationDetails& details) {
+  switch (type.value) {
+    case NotificationType::ACCESSIBILITY_WINDOW_OPENED:
+      OnWindowOpened(Details<const AccessibilityWindowInfo>(details).ptr());
+      break;
+    case NotificationType::ACCESSIBILITY_WINDOW_CLOSED:
+      OnWindowClosed(Details<const AccessibilityWindowInfo>(details).ptr());
+      break;
+    case NotificationType::ACCESSIBILITY_CONTROL_FOCUSED:
+      OnControlFocused(Details<const AccessibilityControlInfo>(details).ptr());
+      break;
+    case NotificationType::ACCESSIBILITY_CONTROL_ACTION:
+      OnControlAction(Details<const AccessibilityControlInfo>(details).ptr());
+      break;
+    case NotificationType::ACCESSIBILITY_TEXT_CHANGED:
+      OnTextChanged(Details<const AccessibilityControlInfo>(details).ptr());
+      break;
+    default:
+      NOTREACHED();
+  }
+}
+
+void ExtensionAccessibilityEventRouter::SetAccessibilityEnabled(bool enabled) {
+  if (enabled_ != enabled) {
+    enabled_ = enabled;
+    if (enabled_) {
+      for (unsigned int i = 0; i < on_enabled_listeners_.size(); i++) {
+        on_enabled_listeners_[i]->Run();
+      }
+    } else {
+      for (unsigned int i = 0; i < on_disabled_listeners_.size(); i++) {
+        on_disabled_listeners_[i]->Run();
+      }
+    }
+  }
+}
+
+bool ExtensionAccessibilityEventRouter::IsAccessibilityEnabled() const {
+  return enabled_;
+}
+
+void ExtensionAccessibilityEventRouter::AddOnEnabledListener(
+    Callback* callback) {
+  on_enabled_listeners_.push_back(callback);
+}
+
+void ExtensionAccessibilityEventRouter::AddOnDisabledListener(
+    Callback* callback) {
+  on_disabled_listeners_.push_back(callback);
+}
+
+void ExtensionAccessibilityEventRouter::OnWindowOpened(
+    const AccessibilityWindowInfo* info) {
+  std::string json_args = ControlInfoToJsonString(info);
+  DispatchEvent(info->profile(), keys::kOnWindowOpened, json_args);
+}
+
+void ExtensionAccessibilityEventRouter::OnWindowClosed(
+    const AccessibilityWindowInfo* info) {
+  std::string json_args = ControlInfoToJsonString(info);
+  DispatchEvent(info->profile(), keys::kOnWindowClosed, json_args);
+}
+
+void ExtensionAccessibilityEventRouter::OnControlFocused(
+    const AccessibilityControlInfo* info) {
+  last_focused_control_dict_.Clear();
+  info->SerializeToDict(&last_focused_control_dict_);
+  std::string json_args = ControlInfoToJsonString(info);
+  DispatchEvent(info->profile(), keys::kOnControlFocused, json_args);
+}
+
+void ExtensionAccessibilityEventRouter::OnControlAction(
+    const AccessibilityControlInfo* info) {
+  std::string json_args = ControlInfoToJsonString(info);
+  DispatchEvent(info->profile(), keys::kOnControlAction, json_args);
+}
+
+void ExtensionAccessibilityEventRouter::OnTextChanged(
+    const AccessibilityControlInfo* info) {
+  std::string json_args = ControlInfoToJsonString(info);
+  DispatchEvent(info->profile(), keys::kOnTextChanged, json_args);
+}
+
+void ExtensionAccessibilityEventRouter::DispatchEvent(
+    Profile* profile,
+    const char* event_name,
+    const std::string& json_args) {
+  if (enabled_ && profile && profile->GetExtensionMessageService()) {
+    profile->GetExtensionMessageService()->
+        DispatchEventToRenderers(event_name, json_args);
+  }
+}
+
+bool SetAccessibilityEnabledFunction::RunImpl() {
+  bool enabled;
+  EXTENSION_FUNCTION_VALIDATE(args_->GetAsBoolean(&enabled));
+  ExtensionAccessibilityEventRouter::GetInstance()
+      ->SetAccessibilityEnabled(enabled);
+  return true;
+}
+
+bool GetFocusedControlFunction::RunImpl() {
+  // Get the serialized dict from the last focused control and return it.
+  // However, if the dict is empty, that means we haven't seen any focus
+  // events yet, so return null instead.
+  ExtensionAccessibilityEventRouter *accessibility_event_router =
+      ExtensionAccessibilityEventRouter::GetInstance();
+  DictionaryValue *last_focused_control_dict =
+      accessibility_event_router->last_focused_control_dict();
+  if (last_focused_control_dict->size()) {
+    result_.reset(last_focused_control_dict->DeepCopyWithoutEmptyChildren());
+  } else {
+    result_.reset(Value::CreateNullValue());
+  }
+  return true;
+}
diff --git a/chrome/browser/extensions/extension_accessibility_api.h b/chrome/browser/extensions/extension_accessibility_api.h
new file mode 100644
index 0000000..afae039
--- /dev/null
+++ b/chrome/browser/extensions/extension_accessibility_api.h
@@ -0,0 +1,96 @@
+// Copyright (c) 2010 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_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
+
+#include <string>
+#include <vector>
+
+#include "base/singleton.h"
+#include "chrome/browser/extensions/extension_function.h"
+#include "chrome/common/accessibility_events.h"
+#include "chrome/common/notification_service.h"
+#include "chrome/common/notification_registrar.h"
+
+// Observes the profile and routes accessibility notifications as events
+// to the extension system.
+class ExtensionAccessibilityEventRouter : public NotificationObserver {
+ public:
+  // Single instance of the event router.
+  static ExtensionAccessibilityEventRouter* GetInstance();
+
+  // Safe to call multiple times.
+  void ObserveProfile(Profile* profile);
+
+  // Get the dict representing the last control that received an
+  // OnControlFocus event.
+  DictionaryValue* last_focused_control_dict() {
+    return &last_focused_control_dict_;
+  }
+
+  // Accessibility support is disabled until an extension expicitly enables
+  // it, so that this extension api has no impact on Chrome's performance
+  // otherwise.  These methods handle enabling, disabling, querying the
+  // status, and installing callbacks to execute when accessibility support
+  // is enabled or disabled.
+  void SetAccessibilityEnabled(bool enabled);
+  bool IsAccessibilityEnabled() const;
+  typedef Callback0::Type Callback;
+  void AddOnEnabledListener(Callback* callback);
+  void AddOnDisabledListener(Callback* callback);
+
+ private:
+  friend struct DefaultSingletonTraits<ExtensionAccessibilityEventRouter>;
+
+  ExtensionAccessibilityEventRouter()
+      : enabled_(false) {}
+  virtual ~ExtensionAccessibilityEventRouter() {}
+
+  // NotificationObserver::Observe.
+  virtual void Observe(NotificationType type,
+                       const NotificationSource& source,
+                       const NotificationDetails& details);
+
+  void OnWindowOpened(const AccessibilityWindowInfo* details);
+  void OnWindowClosed(const AccessibilityWindowInfo* details);
+  void OnControlFocused(const AccessibilityControlInfo* details);
+  void OnControlAction(const AccessibilityControlInfo* details);
+  void OnTextChanged(const AccessibilityControlInfo* details);
+
+  void DispatchEvent(Profile* profile,
+                     const char* event_name,
+                     const std::string& json_args);
+
+  // Used for tracking registrations to history service notifications.
+  NotificationRegistrar registrar_;
+
+  DictionaryValue last_focused_control_dict_;
+
+  bool enabled_;
+  std::vector<Callback*> on_enabled_listeners_;
+  std::vector<Callback*> on_disabled_listeners_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExtensionAccessibilityEventRouter);
+};
+
+// API function that enables or disables accessibility support.  Event
+// listeners are only installed when accessibility support is enabled, to
+// minimize the impact.
+class SetAccessibilityEnabledFunction : public SyncExtensionFunction {
+  virtual ~SetAccessibilityEnabledFunction() {}
+  virtual bool RunImpl();
+  DECLARE_EXTENSION_FUNCTION_NAME(
+      "experimental.accessibility.setAccessibilityEnabled")
+};
+
+// API function that returns the most recent focused control.
+class GetFocusedControlFunction : public SyncExtensionFunction {
+  virtual ~GetFocusedControlFunction() {}
+  virtual bool RunImpl();
+  DECLARE_EXTENSION_FUNCTION_NAME(
+      "experimental.accessibility.getFocusedControl")
+};
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_H_
diff --git a/chrome/browser/extensions/extension_accessibility_api_constants.cc b/chrome/browser/extensions/extension_accessibility_api_constants.cc
new file mode 100644
index 0000000..72d6138
--- /dev/null
+++ b/chrome/browser/extensions/extension_accessibility_api_constants.cc
@@ -0,0 +1,38 @@
+// Copyright (c) 2010 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 "chrome/browser/extensions/extension_accessibility_api_constants.h"
+
+namespace extension_accessibility_api_constants {
+
+// String keys for AccessibilityObject properties.
+const wchar_t kTypeKey[] = L"type";
+const wchar_t kNameKey[] = L"name";
+const wchar_t kDetailsKey[] = L"details";
+const wchar_t kValueKey[] = L"details.value";
+const wchar_t kPasswordKey[] = L"details.isPassword";
+const wchar_t kItemCountKey[] = L"details.itemCount";
+const wchar_t kItemIndexKey[] = L"details.itemIndex";
+const wchar_t kSelectionStartKey[] = L"details.selectionStart";
+const wchar_t kSelectionEndKey[] = L"details.selectionEnd";
+const wchar_t kCheckedKey[] = L"details.isChecked";
+
+// Events.
+const char kOnWindowOpened[] = "experimental.accessibility.onWindowOpened";
+const char kOnWindowClosed[] = "experimental.accessibility.onWindowClosed";
+const char kOnControlFocused[] = "experimental.accessibility.onControlFocused";
+const char kOnControlAction[] = "experimental.accessibility.onControlAction";
+const char kOnTextChanged[] = "experimental.accessibility.onTextChanged";
+
+// Types of controls that can receive accessibility events.
+extern const char kTypeButton[] = "button";
+extern const char kTypeCheckbox[] = "checkbox";
+extern const char kTypeComboBox[] = "combobox";
+extern const char kTypeLink[] = "link";
+extern const char kTypeRadioButton[] = "radiobutton";
+extern const char kTypeTab[] = "tab";
+extern const char kTypeTextBox[] = "textbox";
+extern const char kTypeWindow[] = "window";
+
+}  // namespace extension_accessibility_api_constants
diff --git a/chrome/browser/extensions/extension_accessibility_api_constants.h b/chrome/browser/extensions/extension_accessibility_api_constants.h
new file mode 100644
index 0000000..2020ec8
--- /dev/null
+++ b/chrome/browser/extensions/extension_accessibility_api_constants.h
@@ -0,0 +1,43 @@
+// Copyright (c) 2010 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.
+
+// Constants used to for the Accessibility API.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_CONSTANTS_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_CONSTANTS_H_
+
+namespace extension_accessibility_api_constants {
+
+// Keys.
+extern const wchar_t kTypeKey[];
+extern const wchar_t kNameKey[];
+extern const wchar_t kDetailsKey[];
+extern const wchar_t kValueKey[];
+extern const wchar_t kPasswordKey[];
+extern const wchar_t kItemCountKey[];
+extern const wchar_t kItemIndexKey[];
+extern const wchar_t kSelectionStartKey[];
+extern const wchar_t kSelectionEndKey[];
+extern const wchar_t kCheckedKey[];
+
+// Events.
+extern const char kOnWindowOpened[];
+extern const char kOnWindowClosed[];
+extern const char kOnControlFocused[];
+extern const char kOnControlAction[];
+extern const char kOnTextChanged[];
+
+// Types of controls that can receive accessibility events
+extern const char kTypeButton[];
+extern const char kTypeCheckbox[];
+extern const char kTypeComboBox[];
+extern const char kTypeLink[];
+extern const char kTypeRadioButton[];
+extern const char kTypeTab[];
+extern const char kTypeTextBox[];
+extern const char kTypeWindow[];
+
+};  // namespace extension_accessibility_api_constants
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ACCESSIBILITY_API_CONSTANTS_H_
diff --git a/chrome/browser/extensions/extension_accessibility_apitest.cc b/chrome/browser/extensions/extension_accessibility_apitest.cc
new file mode 100644
index 0000000..692dc9c
--- /dev/null
+++ b/chrome/browser/extensions/extension_accessibility_apitest.cc
@@ -0,0 +1,17 @@
+// Copyright (c) 2009 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 "chrome/browser/extensions/extension_apitest.h"
+
+// This extension is currently only supported on Linux and Chrome OS.
+#if defined(OS_LINUX)
+#define MAYBE_Accessibility Accessibility
+#else
+#define MAYBE_Accessibility DISABLED_Accessibility
+#endif
+
+IN_PROC_BROWSER_TEST_F(ExtensionApiTest, MAYBE_Accessibility) {
+  StartHTTPServer();
+  ASSERT_TRUE(RunExtensionTest("accessibility")) << message_;
+}
diff --git a/chrome/browser/extensions/extension_function_dispatcher.cc b/chrome/browser/extensions/extension_function_dispatcher.cc
index bdba709..936d871 100644
--- a/chrome/browser/extensions/extension_function_dispatcher.cc
+++ b/chrome/browser/extensions/extension_function_dispatcher.cc
@@ -10,6 +10,7 @@
 #include "chrome/browser/browser.h"
 #include "chrome/browser/browser_window.h"
 #include "chrome/browser/extensions/execute_code_in_tab_function.h"
+#include "chrome/browser/extensions/extension_accessibility_api.h"
 #include "chrome/browser/extensions/extension_bookmark_manager_api.h"
 #include "chrome/browser/extensions/extension_bookmarks_module.h"
 #include "chrome/browser/extensions/extension_bookmarks_module_constants.h"
@@ -169,6 +170,10 @@ void FactoryRegistry::ResetFunctions() {
   RegisterFunction<ExtensionTestFailFunction>();
   RegisterFunction<ExtensionTestLogFunction>();
   RegisterFunction<ExtensionTestQuotaResetFunction>();
+
+  // Accessibility.
+  RegisterFunction<GetFocusedControlFunction>();
+  RegisterFunction<SetAccessibilityEnabledFunction>();
 }
 
 void FactoryRegistry::GetAllNames(std::vector<std::string>* names) {
diff --git a/chrome/browser/extensions/extensions_service.cc b/chrome/browser/extensions/extensions_service.cc
index 0846dad..3834ed5 100644
--- a/chrome/browser/extensions/extensions_service.cc
+++ b/chrome/browser/extensions/extensions_service.cc
@@ -14,6 +14,7 @@
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/debugger/devtools_manager.h"
 #include "chrome/browser/extensions/crx_installer.h"
+#include "chrome/browser/extensions/extension_accessibility_api.h"
 #include "chrome/browser/extensions/extension_bookmarks_module.h"
 #include "chrome/browser/extensions/extension_browser_event_router.h"
 #include "chrome/browser/extensions/extension_dom_ui.h"
@@ -164,6 +165,7 @@ void ExtensionsService::Init() {
 
   // Start up the extension event routers.
   ExtensionHistoryEventRouter::GetInstance()->ObserveProfile(profile_);
+  ExtensionAccessibilityEventRouter::GetInstance()->ObserveProfile(profile_);
 
   LoadAllExtensions();