Add an accessibility mode for editable text fields only.

content/common/accessibility_messages.h

Index: content/common/accessibility_messages.h
diff --git a/content/common/accessibility_messages.h b/content/common/accessibility_messages.h
index a37329ef3dca7aa3f7be390cb8769980eaf3b5f8..4e6dc0d27b25ef481443e554415243d7d6b02b0d 100644
--- a/content/common/accessibility_messages.h
+++ b/content/common/accessibility_messages.h
@@ -7,6 +7,7 @@
 
 #include "base/basictypes.h"
 #include "content/common/content_export.h"
+#include "content/common/view_message_enums.h"
 #include "content/public/common/common_param_traits.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_message_utils.h"
@@ -88,6 +89,7 @@ enum AccessibilityNotification {
 
 #endif  // CONTENT_COMMON_ACCESSIBILITY_MESSAGES_H_
 
+IPC_ENUM_TRAITS(AccessibilityMode)
 IPC_ENUM_TRAITS(AccessibilityNotification)
 
 IPC_ENUM_TRAITS(webkit_glue::WebAccessibility::BoolAttribute)
@@ -133,8 +135,9 @@ IPC_STRUCT_END()
 
 // Messages sent from the browser to the renderer.
 
-// Enable accessibility in the renderer process.
-IPC_MESSAGE_ROUTED0(AccessibilityMsg_Enable)
+// Change the accessibility mode in the renderer process.
+IPC_MESSAGE_ROUTED1(AccessibilityMsg_SetMode,
+                    AccessibilityMode)
 
 // Relay a request from assistive technology to set focus to a given node.
 IPC_MESSAGE_ROUTED1(AccessibilityMsg_SetFocus,