Report user actions for interactions with the Windows Settings app.

chrome/browser/win/settings_app_monitor.cc

+// Copyright 2016 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/win/settings_app_monitor.h"
+
+#include <atlbase.h>
+#include <atlcom.h>
+#include <oleauto.h>
+#include <stdint.h>
+#include <uiautomation.h>
+
+#include <algorithm>
+#include <iterator>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/location.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
+#include "base/strings/pattern.h"
+#include "base/strings/string16.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/threading/sequenced_task_runner_handle.h"
+#include "base/win/scoped_comptr.h"
+#include "base/win/scoped_variant.h"
+#include "ui/base/win/atl_module.h"
+
+namespace shell_integration {
+namespace win {
+
+// SettingsAppMonitor::Context -------------------------------------------------
+
+// The guts of the monitor which runs on a dedicated thread in the
+// multi-threaded COM apartment. An instance may be constructed on any thread,
+// but Initialize() must be invoked on a thread in the MTA.
+class SettingsAppMonitor::Context {
+ public:
+  // Returns a new instance ready for initialization and use on another thread.
+  static base::WeakPtr<Context> Create();
+
+  // Deletes the instance.
+  void DeleteOnAutomationThread();
+
+  // Initializes the context, invoking the monitor's |OnInitialized| method via
+  // |monitor_runner| when done. On success, the monitor's other On* methods
+  // will be invoked as events are observed. On failure, this instance
+  // self-destructs after posting |init_callback|. |task_runner| is the runner
+  // for the dedicated thread on which the context lives (owned by its
+  // UIAutomationClient).
+  void Initialize(base::SingleThreadTaskRunner* task_runner,
+                  base::SequencedTaskRunner* monitor_runner,
+                  const base::WeakPtr<SettingsAppMonitor>& monitor);
+
+ private:
+  class EventHandler;
+
+  // The one and only method that may be called from outside of the automation
+  // thread.
+  Context();
+  ~Context();
+
+  // Method(s) invoked by event handlers via weak pointers.
+
+  // Handles a focus change event on |sender|. Dispatches OnAppFocused if
+  // |sender| is the settings app.
+  void HandleFocusChangedEvent(
+      base::win::ScopedComPtr<IUIAutomationElement> sender);
+
+  // Handles the invocation of the element that opens the browser chooser.
+  void HandleChooserInvoked();
+
+  // Handles the invocation of an element in the browser chooser.
+  void HandleBrowserChosen(const base::string16& browser_name);
+
+  // Returns an event handler for all event types of interest.
+  base::win::ScopedComPtr<IUnknown> GetEventHandler();
+
+  // Returns a pointer to the event handler's generic interface.
+  base::win::ScopedComPtr<IUIAutomationEventHandler>
+  GetAutomationEventHandler();
+
+  // Returns a pointer to the event handler's focus changed interface.
+  base::win::ScopedComPtr<IUIAutomationFocusChangedEventHandler>
+  GetFocusChangedEventHandler();
+
+  // Installs an event handler to observe events of interest.
+  HRESULT InstallObservers();
+
+  // The task runner for the automation thread.
+  base::SingleThreadTaskRunner* task_runner_ = nullptr;
+
+  // The task runner on which the owning monitor lives.
+  base::SequencedTaskRunner* monitor_runner_ = nullptr;
+
+  // The monitor that owns this context.
+  base::WeakPtr<SettingsAppMonitor> monitor_;
+
+  // The automation client.
+  base::win::ScopedComPtr<IUIAutomation> automation_;
+
+  // The event handler.
+  base::win::ScopedComPtr<IUnknown> event_handler_;
+
+  // State to suppress duplicate OnAppFocused notifications.
+  bool observed_app_focused_ = false;
+
+  // Weak pointers to the context are given to event handlers.
+  base::WeakPtrFactory<Context> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(Context);
+};
+
+
+// SettingsAppMonitor::Context::EventHandler -----------------------------------
+
+// A handler of events on arbitrary threads in the MTA.
+class SettingsAppMonitor::Context::EventHandler
+    : public ATL::CComObjectRootEx<ATL::CComMultiThreadModel>,
+      public IUIAutomationEventHandler,
+      public IUIAutomationFocusChangedEventHandler {
+ public:
+  BEGIN_COM_MAP(SettingsAppMonitor::Context::EventHandler)
+    COM_INTERFACE_ENTRY(IUIAutomationEventHandler)
+    COM_INTERFACE_ENTRY(IUIAutomationFocusChangedEventHandler)
+  END_COM_MAP()
+
+  EventHandler();
+  ~EventHandler();
+
+  // Initializes the object. Events will be dispatched back to |context| via
+  // |context_runner|.
+  void Initialize(scoped_refptr<base::SingleThreadTaskRunner> context_runner,
+                  const base::WeakPtr<SettingsAppMonitor::Context>& context);
+
+  // IUIAutomationEventHandler:
+  STDMETHOD(HandleAutomationEvent)(IUIAutomationElement *sender,
+                                   EVENTID eventId) override;
+
+  // IUIAutomationFocusChangedEventHandler:
+  STDMETHOD(HandleFocusChangedEvent)(IUIAutomationElement* sender) override;
+
+ private:
+  // The task runner for the monitor client context.
+  scoped_refptr<base::SingleThreadTaskRunner> context_runner_;
+
+  // The monitor context that owns this event handler.
+  base::WeakPtr<SettingsAppMonitor::Context> context_;
+
+  DISALLOW_COPY_AND_ASSIGN(EventHandler);
+};
+
+
+// Utility functions -----------------------------------------------------------
+
+base::string16 GetCachedBstrValue(IUIAutomationElement* element,
+                                  PROPERTYID property_id) {
+  HRESULT result = S_OK;
+  base::win::ScopedVariant var;
+
+  result = element->GetCachedPropertyValueEx(property_id, TRUE, var.Receive());
+  if (FAILED(result))
+    return base::string16();
+
+  if (V_VT(var.ptr()) != VT_BSTR) {
+    LOG_IF(ERROR, V_VT(var.ptr()) != VT_UNKNOWN)
+        << __FUNCTION__ << " property is not a BSTR: " << V_VT(var.ptr());
+    return base::string16();
+  }
+
+  return base::string16(V_BSTR(var.ptr()));
+}
+
+enum class ElementType {
+  // The "Web browser" element in the "Default apps" pane.
+  DEFAULT_BROWSER,
+  // The element representing a browser in the "Choose an app" popup.
+  BROWSER_BUTTON,
+  // Any other element.
+  UNKNOWN,
+};
+
+ElementType DetectElementType(IUIAutomationElement* sender) {
+  base::string16 aid(GetCachedBstrValue(sender, UIA_AutomationIdPropertyId));
+  if (aid == L"SystemSettings_DefaultApps_Browser_Button")
+    return ElementType::DEFAULT_BROWSER;
+  if (base::MatchPattern(aid, L"SystemSettings_DefaultApps_Browser_*_Button"))
+    return ElementType::BROWSER_BUTTON;
+  return ElementType::UNKNOWN;
+}
+
+// Configures a cache request so that it includes all properties needed by
+// DetectElementType() to detect the elements of interest.
+void ConfigureCacheRequest(IUIAutomationCacheRequest* cache_request) {
+  DCHECK(cache_request);
+  cache_request->AddProperty(UIA_AutomationIdPropertyId);
+  cache_request->AddProperty(UIA_NamePropertyId);
+#if ENABLE_DLOG
+  cache_request->AddProperty(UIA_ClassNamePropertyId);
+  cache_request->AddProperty(UIA_ControlTypePropertyId);
+  cache_request->AddProperty(UIA_IsPeripheralPropertyId);
+  cache_request->AddProperty(UIA_ProcessIdPropertyId);
+  cache_request->AddProperty(UIA_ValueValuePropertyId);
+  cache_request->AddProperty(UIA_RuntimeIdPropertyId);
+#endif  // ENABLE_DLOG
+}
+
+
+// Debug logging utility functions ---------------------------------------------
+
+bool GetCachedBoolValue(IUIAutomationElement* element, PROPERTYID property_id) {
+#if ENABLE_DLOG
+  base::win::ScopedVariant var;
+
+  if (FAILED(element->GetCachedPropertyValueEx(property_id, TRUE,
+                                               var.Receive()))) {
+    return false;
+  }
+
+  if (V_VT(var.ptr()) != VT_BOOL) {
+    LOG_IF(ERROR, V_VT(var.ptr()) != VT_UNKNOWN)
+        << __FUNCTION__ << " property is not a BOOL: " << V_VT(var.ptr());
+    return false;
+  }
+
+  return V_BOOL(var.ptr()) != 0;
+#else   // ENABLE_DLOG
+  return false;
+#endif  // !ENABLE_DLOG
+}
+
+int32_t GetCachedInt32Value(IUIAutomationElement* element,
+                            PROPERTYID property_id) {
+#if ENABLE_DLOG
+  base::win::ScopedVariant var;
+
+  if (FAILED(element->GetCachedPropertyValueEx(property_id, TRUE,
+                                               var.Receive()))) {
+    return false;
+  }
+
+  if (V_VT(var.ptr()) != VT_I4) {
+    LOG_IF(ERROR, V_VT(var.ptr()) != VT_UNKNOWN)
+        << __FUNCTION__ << " property is not an I4: " << V_VT(var.ptr());
+    return false;
+  }
+
+  return V_I4(var.ptr());
+#else   // ENABLE_DLOG
+  return 0;
+#endif  // !ENABLE_DLOG
+}
+
+std::vector<int32_t> GetCachedInt32ArrayValue(IUIAutomationElement* element,
+                                              PROPERTYID property_id) {
+  std::vector<int32_t> values;
+#if ENABLE_DLOG
+  base::win::ScopedVariant var;
+
+  if (FAILED(element->GetCachedPropertyValueEx(property_id, TRUE,
+                                               var.Receive()))) {
+    return values;
+  }
+
+  if (V_VT(var.ptr()) != (VT_I4 | VT_ARRAY)) {
+    LOG_IF(ERROR, V_VT(var.ptr()) != VT_UNKNOWN)
+        << __FUNCTION__ << " property is not an I4 array: " << V_VT(var.ptr());
+    return values;
+  }
+
+  SAFEARRAY* array = V_ARRAY(var.ptr());
+  if (SafeArrayGetDim(array) != 1)
+    return values;
+  long lower_bound = 0;
+  long upper_bound = 0;
+  SafeArrayGetLBound(array, 1, &lower_bound);
+  SafeArrayGetUBound(array, 1, &upper_bound);
+  if (lower_bound || upper_bound <= lower_bound)
+    return values;
+  int32_t* data = nullptr;
+  SafeArrayAccessData(array, reinterpret_cast<void**>(&data));
+  values.assign(data, data + upper_bound + 1);
+  SafeArrayUnaccessData(array);
+#endif  // ENABLE_DLOG
+  return values;
+}
+
+std::string IntArrayToString(const std::vector<int32_t>& values) {
+#if ENABLE_DLOG
+  std::vector<std::string> value_strings;
+  std::transform(values.begin(), values.end(),
+                 std::back_inserter(value_strings), &base::IntToString);
+  return base::JoinString(value_strings, ", ");
+#else   // ENABLE_DLOG
+  return std::string();
+#endif  // !ENABLE_DLOG
+}
+
+const char* GetEventName(EVENTID event_id) {
+#if ENABLE_DLOG
+  switch (event_id) {
+    case UIA_ToolTipOpenedEventId:
+      return "UIA_ToolTipOpenedEventId";
+    case UIA_ToolTipClosedEventId:
+      return "UIA_ToolTipClosedEventId";
+    case UIA_StructureChangedEventId:
+      return "UIA_StructureChangedEventId";
+    case UIA_MenuOpenedEventId:
+      return "UIA_MenuOpenedEventId";
+    case UIA_AutomationPropertyChangedEventId:
+      return "UIA_AutomationPropertyChangedEventId";
+    case UIA_AutomationFocusChangedEventId:
+      return "UIA_AutomationFocusChangedEventId";
+    case UIA_AsyncContentLoadedEventId:
+      return "UIA_AsyncContentLoadedEventId";
+    case UIA_MenuClosedEventId:
+      return "UIA_MenuClosedEventId";
+    case UIA_LayoutInvalidatedEventId:
+      return "UIA_LayoutInvalidatedEventId";
+    case UIA_Invoke_InvokedEventId:
+      return "UIA_Invoke_InvokedEventId";
+    case UIA_SelectionItem_ElementAddedToSelectionEventId:
+      return "UIA_SelectionItem_ElementAddedToSelectionEventId";
+    case UIA_SelectionItem_ElementRemovedFromSelectionEventId:
+      return "UIA_SelectionItem_ElementRemovedFromSelectionEventId";
+    case UIA_SelectionItem_ElementSelectedEventId:
+      return "UIA_SelectionItem_ElementSelectedEventId";
+    case UIA_Selection_InvalidatedEventId:
+      return "UIA_Selection_InvalidatedEventId";
+    case UIA_Text_TextSelectionChangedEventId:
+      return "UIA_Text_TextSelectionChangedEventId";
+    case UIA_Text_TextChangedEventId:
+      return "UIA_Text_TextChangedEventId";
+    case UIA_Window_WindowOpenedEventId:
+      return "UIA_Window_WindowOpenedEventId";
+    case UIA_Window_WindowClosedEventId:
+      return "UIA_Window_WindowClosedEventId";
+    case UIA_MenuModeStartEventId:
+      return "UIA_MenuModeStartEventId";
+    case UIA_MenuModeEndEventId:
+      return "UIA_MenuModeEndEventId";
+    case UIA_InputReachedTargetEventId:
+      return "UIA_InputReachedTargetEventId";
+    case UIA_InputReachedOtherElementEventId:
+      return "UIA_InputReachedOtherElementEventId";
+    case UIA_InputDiscardedEventId:
+      return "UIA_InputDiscardedEventId";
+    case UIA_SystemAlertEventId:
+      return "UIA_SystemAlertEventId";
+    case UIA_LiveRegionChangedEventId:
+      return "UIA_LiveRegionChangedEventId";
+    case UIA_HostedFragmentRootsInvalidatedEventId:
+      return "UIA_HostedFragmentRootsInvalidatedEventId";
+    case UIA_Drag_DragStartEventId:
+      return "UIA_Drag_DragStartEventId";
+    case UIA_Drag_DragCancelEventId:
+      return "UIA_Drag_DragCancelEventId";
+    case UIA_Drag_DragCompleteEventId:
+      return "UIA_Drag_DragCompleteEventId";
+    case UIA_DropTarget_DragEnterEventId:
+      return "UIA_DropTarget_DragEnterEventId";
+    case UIA_DropTarget_DragLeaveEventId:
+      return "UIA_DropTarget_DragLeaveEventId";
+    case UIA_DropTarget_DroppedEventId:
+      return "UIA_DropTarget_DroppedEventId";
+    case UIA_TextEdit_TextChangedEventId:
+      return "UIA_TextEdit_TextChangedEventId";
+    case UIA_TextEdit_ConversionTargetChangedEventId:
+      return "UIA_TextEdit_ConversionTargetChangedEventId";
+  }
+#endif  // ENABLE_DLOG
+  return "";
+}
+
+const char* GetControlType(long control_type) {
+#if ENABLE_DLOG
+  switch (control_type) {
+    case UIA_ButtonControlTypeId:
+      return "UIA_ButtonControlTypeId";
+    case UIA_CalendarControlTypeId:
+      return "UIA_CalendarControlTypeId";
+    case UIA_CheckBoxControlTypeId:
+      return "UIA_CheckBoxControlTypeId";
+    case UIA_ComboBoxControlTypeId:
+      return "UIA_ComboBoxControlTypeId";
+    case UIA_EditControlTypeId:
+      return "UIA_EditControlTypeId";
+    case UIA_HyperlinkControlTypeId:
+      return "UIA_HyperlinkControlTypeId";
+    case UIA_ImageControlTypeId:
+      return "UIA_ImageControlTypeId";
+    case UIA_ListItemControlTypeId:
+      return "UIA_ListItemControlTypeId";
+    case UIA_ListControlTypeId:
+      return "UIA_ListControlTypeId";
+    case UIA_MenuControlTypeId:
+      return "UIA_MenuControlTypeId";
+    case UIA_MenuBarControlTypeId:
+      return "UIA_MenuBarControlTypeId";
+    case UIA_MenuItemControlTypeId:
+      return "UIA_MenuItemControlTypeId";
+    case UIA_ProgressBarControlTypeId:
+      return "UIA_ProgressBarControlTypeId";
+    case UIA_RadioButtonControlTypeId:
+      return "UIA_RadioButtonControlTypeId";
+    case UIA_ScrollBarControlTypeId:
+      return "UIA_ScrollBarControlTypeId";
+    case UIA_SliderControlTypeId:
+      return "UIA_SliderControlTypeId";
+    case UIA_SpinnerControlTypeId:
+      return "UIA_SpinnerControlTypeId";
+    case UIA_StatusBarControlTypeId:
+      return "UIA_StatusBarControlTypeId";
+    case UIA_TabControlTypeId:
+      return "UIA_TabControlTypeId";
+    case UIA_TabItemControlTypeId:
+      return "UIA_TabItemControlTypeId";
+    case UIA_TextControlTypeId:
+      return "UIA_TextControlTypeId";
+    case UIA_ToolBarControlTypeId:
+      return "UIA_ToolBarControlTypeId";
+    case UIA_ToolTipControlTypeId:
+      return "UIA_ToolTipControlTypeId";
+    case UIA_TreeControlTypeId:
+      return "UIA_TreeControlTypeId";
+    case UIA_TreeItemControlTypeId:
+      return "UIA_TreeItemControlTypeId";
+    case UIA_CustomControlTypeId:
+      return "UIA_CustomControlTypeId";
+    case UIA_GroupControlTypeId:
+      return "UIA_GroupControlTypeId";
+    case UIA_ThumbControlTypeId:
+      return "UIA_ThumbControlTypeId";
+    case UIA_DataGridControlTypeId:
+      return "UIA_DataGridControlTypeId";
+    case UIA_DataItemControlTypeId:
+      return "UIA_DataItemControlTypeId";
+    case UIA_DocumentControlTypeId:
+      return "UIA_DocumentControlTypeId";
+    case UIA_SplitButtonControlTypeId:
+      return "UIA_SplitButtonControlTypeId";
+    case UIA_WindowControlTypeId:
+      return "UIA_WindowControlTypeId";
+    case UIA_PaneControlTypeId:
+      return "UIA_PaneControlTypeId";
+    case UIA_HeaderControlTypeId:
+      return "UIA_HeaderControlTypeId";
+    case UIA_HeaderItemControlTypeId:
+      return "UIA_HeaderItemControlTypeId";
+    case UIA_TableControlTypeId:
+      return "UIA_TableControlTypeId";
+    case UIA_TitleBarControlTypeId:
+      return "UIA_TitleBarControlTypeId";
+    case UIA_SeparatorControlTypeId:
+      return "UIA_SeparatorControlTypeId";
+    case UIA_SemanticZoomControlTypeId:
+      return "UIA_SemanticZoomControlTypeId";
+    case UIA_AppBarControlTypeId:
+      return "UIA_AppBarControlTypeId";
+  }
+#endif  // ENABLE_DLOG
+  return "";
+}
+
+
+// SettingsAppMonitor::Context::EventHandler -----------------------------------
+
+SettingsAppMonitor::Context::EventHandler::EventHandler() = default;
+
+SettingsAppMonitor::Context::EventHandler::~EventHandler() = default;
+
+void SettingsAppMonitor::Context::EventHandler::Initialize(
+    scoped_refptr<base::SingleThreadTaskRunner> context_runner,
+    const base::WeakPtr<SettingsAppMonitor::Context>& context) {
+  context_runner_ = std::move(context_runner);
+  context_ = context;
+}
+
+HRESULT SettingsAppMonitor::Context::EventHandler::HandleAutomationEvent(
+    IUIAutomationElement* sender,
+    EVENTID event_id) {
+  DVLOG(1) << "event id: " << GetEventName(event_id) << ", automation id: "
+           << GetCachedBstrValue(sender, UIA_AutomationIdPropertyId)
+           << ", name: " << GetCachedBstrValue(sender, UIA_NamePropertyId)
+           << ", control type: " << GetControlType(GetCachedInt32Value(
+                                        sender, UIA_ControlTypePropertyId))
+           << ", is peripheral: "
+           << GetCachedBoolValue(sender, UIA_IsPeripheralPropertyId)
+           << ", class name: "
+           << GetCachedBstrValue(sender, UIA_ClassNamePropertyId)
+           << ", pid: " << GetCachedInt32Value(sender, UIA_ProcessIdPropertyId)
+           << ", value: "
+           << GetCachedBstrValue(sender, UIA_ValueValuePropertyId)
+           << ", runtime id: " << IntArrayToString(GetCachedInt32ArrayValue(
+                                      sender, UIA_RuntimeIdPropertyId));
+
+  switch (DetectElementType(sender)) {
+    case ElementType::DEFAULT_BROWSER:
+      context_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(&SettingsAppMonitor::Context::HandleChooserInvoked,
+                     context_));
+      break;
+    case ElementType::BROWSER_BUTTON: {
+      base::string16 browser_name(
+          GetCachedBstrValue(sender, UIA_NamePropertyId));
+      if (!browser_name.empty()) {
+        context_runner_->PostTask(
+            FROM_HERE,
+            base::Bind(&SettingsAppMonitor::Context::HandleBrowserChosen,
+                       context_, browser_name));
+      }
+      break;
+    }
+    case ElementType::UNKNOWN:
+      break;
+  }
+
+  return S_OK;
+}
+
+HRESULT SettingsAppMonitor::Context::EventHandler::HandleFocusChangedEvent(
+    IUIAutomationElement* sender) {
+  DVLOG(1) << "focus changed for automation id: "
+           << GetCachedBstrValue(sender, UIA_AutomationIdPropertyId)
+           << ", name: " << GetCachedBstrValue(sender, UIA_NamePropertyId)
+           << ", control type: " << GetControlType(GetCachedInt32Value(
+                                        sender, UIA_ControlTypePropertyId))
+           << ", is peripheral: "
+           << GetCachedBoolValue(sender, UIA_IsPeripheralPropertyId)
+           << ", class name: "
+           << GetCachedBstrValue(sender, UIA_ClassNamePropertyId)
+           << ", pid: " << GetCachedInt32Value(sender, UIA_ProcessIdPropertyId)
+           << ", value: "
+           << GetCachedBstrValue(sender, UIA_ValueValuePropertyId)
+           << ", runtime id: " << IntArrayToString(GetCachedInt32ArrayValue(
+                                      sender, UIA_RuntimeIdPropertyId));
+  context_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&SettingsAppMonitor::Context::HandleFocusChangedEvent,
+                 context_,
+                 base::win::ScopedComPtr<IUIAutomationElement>(sender)));
+
+  return S_OK;
+}
+
+// SettingsAppMonitor::Context -------------------------------------------------
+
+base::WeakPtr<SettingsAppMonitor::Context>
+SettingsAppMonitor::Context::Create() {
+  Context* context = new Context();
+  return context->weak_ptr_factory_.GetWeakPtr();
+}
+
+void SettingsAppMonitor::Context::DeleteOnAutomationThread() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  delete this;
+}
+
+void SettingsAppMonitor::Context::Initialize(
+    base::SingleThreadTaskRunner* task_runner,
+    base::SequencedTaskRunner* monitor_runner,
+    const base::WeakPtr<SettingsAppMonitor>& monitor) {
+  // This and all other methods must be called on the automation thread.
+  DCHECK(task_runner->BelongsToCurrentThread());
+  DCHECK(!monitor_runner->RunsTasksOnCurrentThread());
+
+  task_runner_ = task_runner;
+  monitor_runner_ = monitor_runner;
+  monitor_ = monitor;
+
+  HRESULT result = automation_.CreateInstance(CLSID_CUIAutomation, nullptr,
+                                              CLSCTX_INPROC_SERVER);
+  if (SUCCEEDED(result))
+    result = automation_ ? InstallObservers() : E_FAIL;
+
+  // Tell the monitor that initialization is complete one way or the other.
+  monitor_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&SettingsAppMonitor::OnInitialized, monitor_, result));
+
+  // Self-destruct immediately if initialization failed to reduce overhead.
+  if (FAILED(result))
+    delete this;
+}
+
+SettingsAppMonitor::Context::Context() : weak_ptr_factory_(this) {}
+
+SettingsAppMonitor::Context::~Context() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (event_handler_) {
+    event_handler_.Release();
+    automation_->RemoveAllEventHandlers();
+  }
+}
+
+void SettingsAppMonitor::Context::HandleFocusChangedEvent(
+    base::win::ScopedComPtr<IUIAutomationElement> sender) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (DetectElementType(sender.get()) == ElementType::DEFAULT_BROWSER) {
+    if (!observed_app_focused_) {
+      observed_app_focused_ = true;
+      monitor_runner_->PostTask(
+          FROM_HERE, base::Bind(&SettingsAppMonitor::OnAppFocused, monitor_));
+    }
+  } else {
+    observed_app_focused_ = false;
+  }
+}
+
+void SettingsAppMonitor::Context::HandleChooserInvoked() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  monitor_runner_->PostTask(
+      FROM_HERE, base::Bind(&SettingsAppMonitor::OnChooserInvoked, monitor_));
+}
+
+void SettingsAppMonitor::Context::HandleBrowserChosen(
+    const base::string16& browser_name) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  monitor_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&SettingsAppMonitor::OnBrowserChosen, monitor_, browser_name));
+}
+
+base::win::ScopedComPtr<IUnknown>
+SettingsAppMonitor::Context::GetEventHandler() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  if (!event_handler_) {
+    ATL::CComObject<EventHandler>* obj = nullptr;
+    HRESULT result = ATL::CComObject<EventHandler>::CreateInstance(&obj);
+    if (SUCCEEDED(result)) {
+      obj->Initialize(task_runner_, weak_ptr_factory_.GetWeakPtr());
+      obj->QueryInterface(event_handler_.Receive());
+    }
+  }
+  return event_handler_;
+}
+
+base::win::ScopedComPtr<IUIAutomationEventHandler>
+SettingsAppMonitor::Context::GetAutomationEventHandler() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  base::win::ScopedComPtr<IUIAutomationEventHandler> handler;
+  handler.QueryFrom(GetEventHandler().get());
+  return handler;
+}
+
+base::win::ScopedComPtr<IUIAutomationFocusChangedEventHandler>
+SettingsAppMonitor::Context::GetFocusChangedEventHandler() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  base::win::ScopedComPtr<IUIAutomationFocusChangedEventHandler> handler;
+  handler.QueryFrom(GetEventHandler().get());
+  return handler;
+}
+
+HRESULT SettingsAppMonitor::Context::InstallObservers() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(automation_);
+
+  // Create a cache request so that elements received by way of events contain
+  // all data needed for procesing.
+  base::win::ScopedComPtr<IUIAutomationCacheRequest> cache_request;
+  HRESULT result = automation_->CreateCacheRequest(cache_request.Receive());
+  if (FAILED(result))
+    return result;
+  ConfigureCacheRequest(cache_request.get());
+
+  // Observe changes in focus.
+  result = automation_->AddFocusChangedEventHandler(
+      cache_request.get(), GetFocusChangedEventHandler().get());
+  if (FAILED(result))
+    return result;
+
+  // Observe invocations.
+  base::win::ScopedComPtr<IUIAutomationElement> desktop;
+  result = automation_->GetRootElement(desktop.Receive());
+  if (desktop) {
+    result = automation_->AddAutomationEventHandler(
+        UIA_Invoke_InvokedEventId, desktop.get(), TreeScope_Subtree,
+        cache_request.get(), GetAutomationEventHandler().get());
+  }
+
+  return result;
+}
+
+
+// SettingsAppMonitor ----------------------------------------------------------
+
+SettingsAppMonitor::SettingsAppMonitor(Delegate* delegate)
+    : delegate_(delegate),
+      automation_thread_("SettingsAppMonitorAutomation"),
+      weak_ptr_factory_(this) {
+  ui::win::CreateATLModuleIfNeeded();
+  // Start the automation thread and initialize the automation client on it.
+  context_ = Context::Create();
+  automation_thread_.init_com_with_mta(true);
+  automation_thread_.Start();
+  automation_thread_.task_runner()->PostTask(
+      FROM_HERE,
+      base::Bind(&SettingsAppMonitor::Context::Initialize, context_,
+                 base::Unretained(automation_thread_.task_runner().get()),
+                 base::Unretained(base::SequencedTaskRunnerHandle::Get().get()),
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+SettingsAppMonitor::~SettingsAppMonitor() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  // context_ is still valid when the caller destroys the instance before the
+  // callback(s) have fired. In this case, delete the context on the automation
+  // thread before joining with it. DeleteSoon is not used because the monitor
+  // has only a WeakPtr to the context that is bound to the automation thread.
+  automation_thread_.task_runner()->PostTask(
+      FROM_HERE,
+      base::Bind(&SettingsAppMonitor::Context::DeleteOnAutomationThread,
+                 context_));
+}
+
+void SettingsAppMonitor::OnInitialized(HRESULT result) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  delegate_->OnInitialized(result);
+}
+
+void SettingsAppMonitor::OnAppFocused() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  delegate_->OnAppFocused();
+}
+
+void SettingsAppMonitor::OnChooserInvoked() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  delegate_->OnChooserInvoked();
+}
+
+void SettingsAppMonitor::OnBrowserChosen(const base::string16& browser_name) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  delegate_->OnBrowserChosen(browser_name);
+}
+
+}  // namespace win
+}  // namespace shell_integration