Revert "Ensure Windows accessibility is enabled properly."

This reverts commit 33d3164a.

Reason for revert: Breaks NVDA / JAWS

Original change's description:
> Ensure Windows accessibility is enabled properly.
> 
> http://crrev.com/c/1192062 made it so that we don't enable accessibility
> as often. The idea was to only enable accessibility if we get a call to
> IAccessible2, or to both get_accName and a response to our alert message
> on a honeypot window.
> 
> However, this only worked if we constructed at least one
> BrowserAccessibilityManager. In cases where the external client
> never explored and discovered a BrowserAccessibilityManager, the
> IAccessible2UsageObserver wasn't registered yet.
> 
> As a fix, move the IAccessible2UsageObserver code to part of
> BrowserAccessibilityStateImpl.
> 
> Bug: 878072
> Change-Id: Iadcbd032fa1d6f635bbb99c1e130d384efe0d9b1
> Reviewed-on: https://chromium-review.googlesource.com/1234267
> Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
> Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#593233}

TBR=dmazzoni@chromium.org,aleventhal@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 878072
Change-Id: I482cb7e3fa19f5f6357c4bc28f44cb20272142cd
Reviewed-on: https://chromium-review.googlesource.com/1240473Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593574}

content/browser/accessibility/browser_accessibility_manager_win.cc

@@ -19,6 +19,10 @@
 
 namespace content {
 
+// See OnScreenReaderHoneyPotQueried, below.
+bool g_screen_reader_honeypot_queried = false;
+bool g_acc_name_called = false;
+
 // static
 BrowserAccessibilityManager* BrowserAccessibilityManager::Create(
     const ui::AXTreeUpdate& initial_tree,
@@ -40,6 +44,7 @@ BrowserAccessibilityManagerWin::BrowserAccessibilityManagerWin(
       load_complete_pending_(false) {
   ui::win::CreateATLModuleIfNeeded();
   Initialize(initial_tree);
+  ui::GetIAccessible2UsageObserverList().AddObserver(this);
 }
 
 BrowserAccessibilityManagerWin::~BrowserAccessibilityManagerWin() {
@@ -47,6 +52,7 @@ BrowserAccessibilityManagerWin::~BrowserAccessibilityManagerWin() {
   // destructor, otherwise our overrides of functions like
   // OnNodeWillBeDeleted won't be called.
   tree_.reset(NULL);
+  ui::GetIAccessible2UsageObserverList().RemoveObserver(this);
 }
 
 // static
@@ -70,6 +76,38 @@ HWND BrowserAccessibilityManagerWin::GetParentHWND() {
   return delegate->AccessibilityGetAcceleratedWidget();
 }
 
+void BrowserAccessibilityManagerWin::OnIAccessible2Used() {
+  // When IAccessible2 APIs have been used elsewhere in the codebase,
+  // enable basic web accessibility support. (Full screen reader support is
+  // detected later when specific more advanced APIs are accessed.)
+  BrowserAccessibilityStateImpl::GetInstance()->AddAccessibilityModeFlags(
+      ui::AXMode::kNativeAPIs | ui::AXMode::kWebContents);
+}
+
+void BrowserAccessibilityManagerWin::OnScreenReaderHoneyPotQueried() {
+  // We used to trust this as a signal that a screen reader is running,
+  // but it's been abused. Now only enable accessibility if we also
+  // detect a call to get_accName.
+  if (g_screen_reader_honeypot_queried)
+    return;
+  g_screen_reader_honeypot_queried = true;
+  if (g_acc_name_called) {
+    BrowserAccessibilityStateImpl::GetInstance()->AddAccessibilityModeFlags(
+        ui::AXMode::kNativeAPIs | ui::AXMode::kWebContents);
+  }
+}
+
+void BrowserAccessibilityManagerWin::OnAccNameCalled() {
+  // See OnScreenReaderHoneyPotQueried, above.
+  if (g_acc_name_called)
+    return;
+  g_acc_name_called = true;
+  if (g_screen_reader_honeypot_queried) {
+    BrowserAccessibilityStateImpl::GetInstance()->AddAccessibilityModeFlags(
+        ui::AXMode::kNativeAPIs | ui::AXMode::kWebContents);
+  }
+}
+
 void BrowserAccessibilityManagerWin::UserIsReloading() {
   if (GetRoot())
     FireWinAccessibilityEvent(IA2_EVENT_DOCUMENT_RELOAD, GetRoot());

content/browser/accessibility/browser_accessibility_manager_win.h

@@ -18,7 +18,8 @@ class BrowserAccessibilityWin;
 
 // Manages a tree of BrowserAccessibilityWin objects.
 class CONTENT_EXPORT BrowserAccessibilityManagerWin
-    : public BrowserAccessibilityManager {
+    : public BrowserAccessibilityManager,
+      public ui::IAccessible2UsageObserver {
  public:
   BrowserAccessibilityManagerWin(
       const ui::AXTreeUpdate& initial_tree,
@@ -32,6 +33,11 @@ class CONTENT_EXPORT BrowserAccessibilityManagerWin
   // Get the closest containing HWND.
   HWND GetParentHWND();
 
+  // IAccessible2UsageObserver
+  void OnIAccessible2Used() override;
+  void OnScreenReaderHoneyPotQueried() override;
+  void OnAccNameCalled() override;
+
   // BrowserAccessibilityManager methods
   void UserIsReloading() override;
   BrowserAccessibility* GetFocus() override;

content/browser/accessibility/browser_accessibility_state_impl.cc

@@ -168,8 +168,6 @@ ui::AXMode BrowserAccessibilityStateImpl::GetAccessibilityMode() const {
 }
 
 #if !defined(OS_WIN) && !defined(OS_MACOSX)
-void BrowserAccessibilityStateImpl::PlatformInitialize() {}
-
 void BrowserAccessibilityStateImpl::UpdatePlatformSpecificHistograms() {
 }
 #endif

content/browser/accessibility/browser_accessibility_state_impl.h

@@ -84,7 +84,6 @@ class CONTENT_EXPORT BrowserAccessibilityStateImpl
   // Leaky singleton, destructor generally won't be called.
   ~BrowserAccessibilityStateImpl() override;
 
-  void PlatformInitialize();
   void UpdatePlatformSpecificHistograms();
 
   ui::AXMode accessibility_mode_;

content/browser/accessibility/browser_accessibility_state_impl_mac.mm

@@ -18,8 +18,6 @@
 
 namespace content {
 
-void BrowserAccessibilityStateImpl::PlatformInitialize() {}
-
 void BrowserAccessibilityStateImpl::UpdatePlatformSpecificHistograms() {
   // NOTE: This function is running on the file thread.
   NSWorkspace* workspace = [NSWorkspace sharedWorkspace];

content/browser/accessibility/browser_accessibility_state_impl_win.cc

@@ -15,65 +15,9 @@
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_util.h"
-#include "ui/accessibility/platform/ax_platform_node_win.h"
 
 namespace content {
 
-namespace {
-
-// Enables accessibility based on three possible clues that indicate
-// accessibility API usage.
-//
-// TODO(dmazzoni): Rename IAccessible2UsageObserver to something more general.
-class WindowsAccessibilityEnabler : public ui::IAccessible2UsageObserver {
- public:
-  WindowsAccessibilityEnabler() {}
-
- private:
-  // IAccessible2UsageObserver
-  void OnIAccessible2Used() override {
-    // When IAccessible2 APIs have been used elsewhere in the codebase,
-    // enable basic web accessibility support. (Full screen reader support is
-    // detected later when specific more advanced APIs are accessed.)
-    BrowserAccessibilityStateImpl::GetInstance()->AddAccessibilityModeFlags(
-        ui::AXMode::kNativeAPIs | ui::AXMode::kWebContents);
-  }
-
-  void OnScreenReaderHoneyPotQueried() override {
-    // We used to trust this as a signal that a screen reader is running,
-    // but it's been abused. Now only enable accessibility if we also
-    // detect a call to get_accName.
-    if (screen_reader_honeypot_queried_)
-      return;
-    screen_reader_honeypot_queried_ = true;
-    if (acc_name_called_) {
-      BrowserAccessibilityStateImpl::GetInstance()->AddAccessibilityModeFlags(
-          ui::AXMode::kNativeAPIs | ui::AXMode::kWebContents);
-    }
-  }
-
-  void OnAccNameCalled() override {
-    // See OnScreenReaderHoneyPotQueried, above.
-    if (acc_name_called_)
-      return;
-    acc_name_called_ = true;
-    if (screen_reader_honeypot_queried_) {
-      BrowserAccessibilityStateImpl::GetInstance()->AddAccessibilityModeFlags(
-          ui::AXMode::kNativeAPIs | ui::AXMode::kWebContents);
-    }
-  }
-
-  bool screen_reader_honeypot_queried_ = false;
-  bool acc_name_called_ = false;
-};
-
-}  // namespace
-
-void BrowserAccessibilityStateImpl::PlatformInitialize() {
-  ui::GetIAccessible2UsageObserverList().AddObserver(
-      new WindowsAccessibilityEnabler());
-}
-
 void BrowserAccessibilityStateImpl::UpdatePlatformSpecificHistograms() {
   // NOTE: this method is run from the file thread to reduce jank, since
   // there's no guarantee these system calls will return quickly. Be careful