Implement asynchronous interface/plumbing for GetDefaultPrintSettings.

ppapi/cpp/dev/printing_dev.h

Index: ppapi/cpp/dev/printing_dev.h
diff --git a/ppapi/cpp/dev/printing_dev.h b/ppapi/cpp/dev/printing_dev.h
index eb20e563641f039bebad9f100661b71afd9d29fa..e5654dfad276d6bf26d75ade95035210dfd58320 100644
--- a/ppapi/cpp/dev/printing_dev.h
+++ b/ppapi/cpp/dev/printing_dev.h
@@ -11,6 +11,7 @@
 
 namespace pp {
 
+class CompletionCallback;
 class Instance;
 
 // You would typically use this either via inheritance on your instance or
@@ -35,10 +36,16 @@ class Printing_Dev {
   // interface.
   static bool IsAvailable();
 
-  // Outputs the default print settings for the default printer into
-  // |print_settings|. Returns false on error.
+  // TODO(raymes): This is deprecated in PPB_Printing_Dev 0.7. Remove this
+  // once Flash has been modified not to use this function.
   bool GetDefaultPrintSettings(PP_PrintSettings_Dev* print_settings) const;
 
+  // Outputs the default print settings for the default printer into
+  // |print_settings|. The completion callback is called when the settings are
+  // ready to be used.
+  int32_t GetDefaultPrintSettings(PP_PrintSettings_Dev* print_settings,
+                                  const CompletionCallback& callback) const;
+
  private:
   InstanceHandle associated_instance_;
 };