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

content/public/browser/browser_accessibility_state.h

Index: content/public/browser/browser_accessibility_state.h
diff --git a/content/public/browser/browser_accessibility_state.h b/content/public/browser/browser_accessibility_state.h
index 16cf706d3867dbd6980bd406224fa9fc4ddca612..7d575858e73003b14f8d4bac1c09022597869149 100644
--- a/content/public/browser/browser_accessibility_state.h
+++ b/content/public/browser/browser_accessibility_state.h
@@ -6,6 +6,7 @@
 #define CONTENT_PUBLIC_BROWSER_BROWSER_ACCESSIBILITY_STATE_H_
 
 #include "base/callback_forward.h"
+
 #include "content/common/content_export.h"
 
 namespace content {
@@ -20,8 +21,11 @@ class CONTENT_EXPORT BrowserAccessibilityState {
   // Returns the singleton instance.
   static BrowserAccessibilityState* GetInstance();
 
-  // Called when accessibility is enabled manually (via command-line flag).
-  virtual void OnAccessibilityEnabledManually() = 0;
+  // Called when accessibility is enabled manually.

[Jói, 2013/05/02 09:52:03]

An explanation here (and line 27) of why the comment says "manually" whereas the
method name says "ByExtensionAPI" might be helpful.

+  virtual void OnAccessibilityEnabledByExtensionAPI() = 0;

[jam, 2013/05/02 15:50:20]

see http://www.chromium.org/developers/content-module
content doesn't know about extensions, as that's a concept from a higher level
module (chrome).

please don't mention extensions in these api. instead make the name something
like EnableAccessibility/DisableAccessibility.

nit: in general, "On" as a prefix is used for IPC message handlers.

+
+  // Called when accessibility is disabled manually.
+  virtual void OnAccessibilityDisabledByExtensionAPI() = 0;
 
   // Called when screen reader client is detected.
   virtual void OnScreenReaderDetected() = 0;