Bug 761589 - Refactor accessibility.force_disabled to work on Mac too and make it tri-state. r=tbsaunde

accessible/src/base/nsAccessibilityService.cpp

@@ -63,6 +63,7 @@
 #include "nsTextFragment.h"
 #include "mozilla/FunctionTimer.h"
 #include "mozilla/dom/Element.h"
+#include "mozilla/Preferences.h"
 #include "mozilla/Services.h"
 #include "mozilla/Util.h"
 
@@ -1819,8 +1820,30 @@ nsAccessibilityService::CreateAccessibleForXULTree(nsIContent* aContent,
 // Services
 ////////////////////////////////////////////////////////////////////////////////
 
-mozilla::a11y::FocusManager*
-mozilla::a11y::FocusMgr()
+namespace mozilla {
+namespace a11y {
+
+FocusManager*
+FocusMgr()
 {
   return nsAccessibilityService::gAccessibilityService;
 }
+
+EPlatformDisabledState
+PlatformDisabledState()
+{
+  static int disabledState = 0xff;
+
+  if (disabledState == 0xff) {
+    disabledState = Preferences::GetInt("accessibility.force_disabled", 0);
+    if (disabledState < ePlatformIsForceEnabled)
+      disabledState = ePlatformIsForceEnabled;
+    else if (disabledState > ePlatformIsDisabled)
+      disabledState = ePlatformIsDisabled;
+  }
+
+  return (EPlatformDisabledState)disabledState;
+}
+
+}
+}

accessible/src/base/nsAccessibilityService.h

@@ -26,6 +26,17 @@ namespace a11y {
  */
 FocusManager* FocusMgr();
 
+enum EPlatformDisabledState {
+  ePlatformIsForceEnabled = -1,
+  ePlatformIsEnabled = 0,
+  ePlatformIsDisabled = 1
+};
+
+/**
+ * Return the platform disabled state.
+ */
+EPlatformDisabledState PlatformDisabledState();
+
 #ifdef MOZ_ACCESSIBILITY_ATK
 /**
  * Perform initialization that should be done as soon as possible, in order

accessible/src/mac/ApplicationAccessibleWrap.mm

@@ -13,12 +13,14 @@
 namespace mozilla {
 namespace a11y {
 
+// Mac a11y whitelisting
 static bool sA11yShouldBeEnabled = false;
 
 bool
 ShouldA11yBeEnabled()
 {
-  return sA11yShouldBeEnabled;
+  EPlatformDisabledState disabledState = PlatformDisabledState();
+  return (disabledState == ePlatformIsForceEnabled) || ((disabledState == ePlatformIsEnabled) && sA11yShouldBeEnabled);
 }
 
 }

modules/libpref/src/init/all.js

@@ -253,10 +253,6 @@ pref("accessibility.browsewithcaret_shortcut.enabled", true);
 pref("accessibility.tabfocus", 7);
 pref("accessibility.tabfocus_applies_to_xul", false);
 
-// Forcibly disable a11y on win32, even if something attempts
-// to enable it.
-pref("accessibility.win32.force_disabled", false);
-
 // On OS X, we follow the "Click in the scrollbar to:" system preference
 // unless this preference was set manually
 pref("ui.scrollToClick", 0);
@@ -266,6 +262,19 @@ pref("ui.scrollToClick", 0);
 pref("accessibility.tabfocus_applies_to_xul", true);
 #endif
 
+// We want the ability to forcibly disable platform a11y, because
+// some non-a11y-related components attempt to bring it up.  See bug
+// 538530 for details about Windows; we have a pref here that allows it
+// to be disabled for performance and testing resons.
+// See bug 761589 for the crossplatform aspect.
+//
+// This pref is checked only once, and the browser needs a restart to
+// pick up any changes.
+//
+// Values are -1 always on. 1 always off, 0 is auto as some platform perform
+// further checks.
+pref("accessibility.force_disabled", 0);
+
 pref("focusmanager.testmode", false);
 
 pref("accessibility.usetexttospeech", "");

widget/windows/nsWindow.cpp

@@ -137,6 +137,7 @@
 #if defined(ACCESSIBILITY)
 #include "oleidl.h"
 #include <winuser.h>
+#include "nsAccessibilityService.h"
 #include "nsIAccessibleDocument.h"
 #if !defined(WINABLEAPI)
 #include <winable.h>
@@ -7337,27 +7338,9 @@ bool nsWindow::AssociateDefaultIMC(bool aAssociate)
 Accessible*
 nsWindow::GetRootAccessible()
 {
-  // We want the ability to forcibly disable a11y on windows, because
-  // some non-a11y-related components attempt to bring it up.  See bug
-  // 538530 for details; we have a pref here that allows it to be disabled
-  // for performance and testing resons.
-  //
-  // This pref is checked only once, and the browser needs a restart to
-  // pick up any changes.
-  static int accForceDisable = -1;
-
-  if (accForceDisable == -1) {
-    const char* kPrefName = "accessibility.win32.force_disabled";
-    if (Preferences::GetBool(kPrefName, false)) {
-      accForceDisable = 1;
-    } else {
-      accForceDisable = 0;
-    }
-  }
-
-  // If the pref was true, return null here, disabling a11y.
-  if (accForceDisable)
-      return nsnull;
+  // If the pref was ePlatformIsDisabled, return null here, disabling a11y.
+  if (a11y::PlatformDisabledState() == a11y::ePlatformIsDisabled)
+    return nsnull;
 
   if (mInDtor || mOnDestroyCalled || mWindowType == eWindowType_invisible) {
     return nsnull;