Implement put_accvalue for textfields and location bar.

ui/base/accessibility/accessible_view_state.h

Index: ui/base/accessibility/accessible_view_state.h
diff --git a/ui/base/accessibility/accessible_view_state.h b/ui/base/accessibility/accessible_view_state.h
index 9553d1cffa1f01c5f5e7172e7e952e87f4237f12..88c31cb0444f1a4d047fbfd29588b21bd150fee4 100644
--- a/ui/base/accessibility/accessible_view_state.h
+++ b/ui/base/accessibility/accessible_view_state.h
@@ -6,6 +6,7 @@
 #define UI_BASE_ACCESSIBILITY_ACCESSIBLE_VIEW_STATE_H_
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/strings/string16.h"
 #include "ui/base/accessibility/accessibility_types.h"
 #include "ui/base/ui_export.h"
@@ -54,6 +55,18 @@ struct UI_EXPORT AccessibleViewState {
   // index and count should be -1 otherwise.
   int index;
   int count;
+
+  // An optional callback that can be used by accessibility clients to
+  // set the string value of this view. This only applies to roles where
+  // setting the value makes sense, like a text box. Not often used by
+  // screen readers, but often used by automation software to script
+  // things like logging into portals or filling forms.
+  //
+  // This callback is not expected to persist beyond the scope of the

[msw, 2013/08/31 20:22:36]

I think it'd be better to try to use WeakPtr than base::Unretained. Then revise
this notice to explain that the Callback is only valid for the lifetime of the
associated view, and will simply/safely no-op otherwise.

[dmazzoni, 2013/09/03 20:20:11]

Done.

+  // function that immediately requested the AccessibleViewState. It should
+  // be used immediately or deleted. Accessible views should use
+  // base::Unretained when binding the callback.
+  base::Callback<void(const base::string16&)> set_value_callback;
 };
 
 }  // namespace ui