Bug 1956415 part 1: Add Compatibility::IsUiaEnabled. r=morgan

Initially, this just checks the accessibility.uia.enable pref.
Other checks will be added in subsequent patches.
All callers which previously checked the pref directly now call this function.

Differential Revision: https://phabricator.services.mozilla.com/D243244

Author: jcsteh

accessible/windows/ia2/ia2Accessible.cpp

@@ -20,7 +20,6 @@
 #include "nsCoreUtils.h"
 #include "nsIAccessibleTypes.h"
 #include "mozilla/a11y/PDocAccessible.h"
-#include "mozilla/StaticPrefs_accessibility.h"
 #include "Relation.h"
 #include "TextRange-inl.h"
 #include "nsAccessibilityService.h"
@@ -355,7 +354,7 @@ ia2Accessible::get_windowHandle(HWND* aWindowHandle) {
   if (!acc) return CO_E_OBJNOTCONNECTED;
 
   *aWindowHandle = MsaaAccessible::GetHWNDFor(acc);
-  if (!*aWindowHandle && !StaticPrefs::accessibility_uia_enable()) {
+  if (!*aWindowHandle && !Compatibility::IsUiaEnabled()) {
     // Bug 1890155: This can happen if a document is detached from its embedder.
     // The document might be about to die or it might be moving to a different
     // embedder; e.g. a tab in a different window. The IA2 -> UIA proxy may

accessible/windows/msaa/Compatibility.cpp

@@ -214,3 +214,9 @@ SuppressionReasons Compatibility::A11ySuppressionReasons() {
   }
   return reasons;
 }
+
+/* static */
+bool Compatibility::IsUiaEnabled() {
+  // This is the only function which should call the UIA pref function directly.
+  return StaticPrefs::accessibility_uia_enable_DoNotUseDirectly();
+}

accessible/windows/msaa/Compatibility.h

@@ -98,6 +98,14 @@ class Compatibility {
   }
   static SuppressionReasons A11ySuppressionReasons();
 
+  /**
+   * Returns true if Gecko's native UI Automation implementation is enabled.
+   * This is primarily configured via the accessibility.uia.enable pref.
+   * However, it might be disabled if Gecko detects known incompatible clients
+   * which would otherwise break.
+   */
+  static bool IsUiaEnabled();
+
  private:
   Compatibility();
   Compatibility(const Compatibility&);

accessible/windows/msaa/LazyInstantiator.cpp

@@ -12,7 +12,6 @@
 #include "mozilla/a11y/Platform.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/mscom/ProcessRuntime.h"
-#include "mozilla/StaticPrefs_accessibility.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WinHeaderOnlyUtils.h"
 #include "MsaaRootAccessible.h"
@@ -111,7 +110,7 @@ already_AddRefed<IAccessible> LazyInstantiator::GetRootAccessible(HWND aHwnd) {
 /* static */
 already_AddRefed<IRawElementProviderSimple> LazyInstantiator::GetRootUia(
     HWND aHwnd) {
-  if (!StaticPrefs::accessibility_uia_enable()) {
+  if (!Compatibility::IsUiaEnabled()) {
     return nullptr;
   }
   return GetRoot<IRawElementProviderSimple>(aHwnd);
@@ -381,7 +380,7 @@ LazyInstantiator::MaybeResolveRoot() {
     }
     // mWeakAccessible is weak, so don't hold a strong ref
     mWeakAccessible->Release();
-    if (StaticPrefs::accessibility_uia_enable()) {
+    if (Compatibility::IsUiaEnabled()) {
       hr = mRealRootUnk->QueryInterface(IID_IRawElementProviderSimple,
                                         (void**)&mWeakUia);
       if (FAILED(hr)) {
@@ -418,7 +417,7 @@ IMPL_IUNKNOWN_QUERY_IFACE_AMBIGIOUS(IUnknown, IAccessible)
 IMPL_IUNKNOWN_QUERY_IFACE(IAccessible)
 IMPL_IUNKNOWN_QUERY_IFACE(IDispatch)
 IMPL_IUNKNOWN_QUERY_IFACE(IServiceProvider)
-if (StaticPrefs::accessibility_uia_enable()) {
+if (Compatibility::IsUiaEnabled()) {
   IMPL_IUNKNOWN_QUERY_IFACE(IRawElementProviderSimple)
 }
 // See EnableBlindAggregation for comments.

accessible/windows/msaa/MsaaAccessible.cpp

@@ -14,7 +14,6 @@
 #include "mozilla/a11y/AccessibleWrap.h"
 #include "mozilla/a11y/Compatibility.h"
 #include "mozilla/a11y/DocAccessibleParent.h"
-#include "mozilla/StaticPrefs_accessibility.h"
 #include "MsaaAccessible.h"
 #include "MsaaDocAccessible.h"
 #include "MsaaRootAccessible.h"
@@ -518,7 +517,7 @@ MsaaAccessible::QueryInterface(REFIID iid, void** ppv) {
     if (SUCCEEDED(hr)) {
       return hr;
     }
-    if (StaticPrefs::accessibility_uia_enable()) {
+    if (Compatibility::IsUiaEnabled()) {
       hr = uiaRawElmProvider::QueryInterface(iid, ppv);
       if (SUCCEEDED(hr)) {
         return hr;

accessible/windows/msaa/MsaaRootAccessible.cpp

@@ -3,9 +3,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "mozilla/a11y/Compatibility.h"
 #include "mozilla/a11y/DocAccessibleParent.h"
 #include "mozilla/dom/BrowserParent.h"
-#include "mozilla/StaticPrefs_accessibility.h"
 #include "mozilla/WindowsVersion.h"
 #include "MsaaRootAccessible.h"
 #include "Relation.h"
@@ -43,7 +43,7 @@ MsaaRootAccessible::InternalQueryInterface(REFIID aIid, void** aOutInterface) {
     return S_OK;
   }
 
-  if (StaticPrefs::accessibility_uia_enable() &&
+  if (Compatibility::IsUiaEnabled() &&
       aIid == IID_IRawElementProviderFragmentRoot) {
     RefPtr<IRawElementProviderFragmentRoot> root = this;
     root.forget(aOutInterface);

accessible/windows/msaa/ServiceProvider.cpp

@@ -15,8 +15,8 @@
 #include "RootAccessible.h"
 #include "uiaRawElmProvider.h"
 
+#include "mozilla/a11y/Compatibility.h"
 #include "mozilla/a11y/DocAccessibleChild.h"
-#include "mozilla/StaticPrefs_accessibility.h"
 
 #include "ISimpleDOM.h"
 
@@ -87,8 +87,7 @@ ServiceProvider::QueryService(REFGUID aGuidService, REFIID aIID,
       aGuidService == IID_SimpleDOMDeprecated ||
       aGuidService == IID_IAccessible || aGuidService == IID_IAccessible2 ||
       // UIA IAccessibleEx
-      (aGuidService == IID_IAccessibleEx &&
-       StaticPrefs::accessibility_uia_enable())) {
+      (aGuidService == IID_IAccessibleEx && Compatibility::IsUiaEnabled())) {
     return mMsaa->QueryInterface(aIID, aInstancePtr);
   }
 

accessible/windows/uia/uiaRawElmProvider.cpp

@@ -17,8 +17,8 @@
 #include "ia2AccessibleTable.h"
 #include "ia2AccessibleTableCell.h"
 #include "LocalAccessible-inl.h"
+#include "mozilla/a11y/Compatibility.h"
 #include "mozilla/a11y/RemoteAccessible.h"
-#include "mozilla/StaticPrefs_accessibility.h"
 #include "MsaaAccessible.h"
 #include "MsaaRootAccessible.h"
 #include "nsAccessibilityService.h"
@@ -140,7 +140,7 @@ Accessible* uiaRawElmProvider::Acc() const {
 /* static */
 void uiaRawElmProvider::RaiseUiaEventForGeckoEvent(Accessible* aAcc,
                                                    uint32_t aGeckoEvent) {
-  if (!StaticPrefs::accessibility_uia_enable()) {
+  if (!Compatibility::IsUiaEnabled()) {
     return;
   }
   auto* uia = MsaaAccessible::GetFrom(aAcc);
@@ -220,7 +220,7 @@ void uiaRawElmProvider::RaiseUiaEventForGeckoEvent(Accessible* aAcc,
 void uiaRawElmProvider::RaiseUiaEventForStateChange(Accessible* aAcc,
                                                     uint64_t aState,
                                                     bool aEnabled) {
-  if (!StaticPrefs::accessibility_uia_enable()) {
+  if (!Compatibility::IsUiaEnabled()) {
     return;
   }
   auto* uia = MsaaAccessible::GetFrom(aAcc);

modules/libpref/init/StaticPrefList.yaml

@@ -293,6 +293,7 @@
   type: bool
   value: false
   mirror: always
+  do_not_use_directly: true
 
 # Whether to avoid accessibility activation on Windows shortly after clipboard
 # copy.