Do not toggle Applist with Search key press when accessibility is enabled.

ash/shell_delegate.h

Index: ash/shell_delegate.h
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index db7d634e8dbf8de410d3151150a85a6507901e3f..e4f4ee8f39ae2b9193eceb8207ff15c2eb9b1be7 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -97,6 +97,9 @@ class ASH_EXPORT ShellDelegate {
   // for accessibility.
   virtual void ToggleSpokenFeedback() = 0;
 
+  // Returns true if spoken feedback is enabled.
+  virtual bool IsSpokenFeedbackEnabled() const = 0;
+
   // Invoked to create an AppListViewDelegate. Shell takes the ownership of
   // the created delegate.
   virtual app_list::AppListViewDelegate* CreateAppListViewDelegate() = 0;