Adds new experimental accessibility extension api to enable or disable native accessibility.

chrome/browser/accessibility/accessibility_extension_api.cc

Index: chrome/browser/accessibility/accessibility_extension_api.cc
diff --git a/chrome/browser/accessibility/accessibility_extension_api.cc b/chrome/browser/accessibility/accessibility_extension_api.cc
index 95ed9c2e1da86243736717f23fc84f79d9fdc3fc..6d9e5e23ba07d00562f2eb5f7031a3079820f97b 100644
--- a/chrome/browser/accessibility/accessibility_extension_api.cc
+++ b/chrome/browser/accessibility/accessibility_extension_api.cc
@@ -17,6 +17,7 @@
 #include "chrome/browser/infobars/infobar_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_notification_types.h"
+#include "content/public/browser/browser_accessibility_state.h"
 #include "content/public/browser/notification_service.h"
 #include "extensions/common/error_utils.h"
 
@@ -179,6 +180,19 @@ bool AccessibilitySetAccessibilityEnabledFunction::RunImpl() {
   return true;
 }
 
+bool AccessibilitySetNativeAccessibilityEnabledFunction::RunImpl() {
+  bool enabled;
+  EXTENSION_FUNCTION_VALIDATE(args_->GetBoolean(0, &enabled));
+  if (enabled) {
+    content::BrowserAccessibilityState::GetInstance()->
+        OnAccessibilityEnabledManually();

[dmazzoni, 2013/04/30 23:25:08]

Call this OnAccessibilityEnabledByExtensionAPI and
OnAccessibilityDisabledByExtensionAPI, I'd like to distinguish between manually
and by extension api in the histograms while we're at it.

+  } else {
+    content::BrowserAccessibilityState::GetInstance()->
+        OnAccessibilityDisabledManually();
+  }
+  return true;
+}
+
 bool AccessibilityGetFocusedControlFunction::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