Send request to show print system dialog to Metro.

printing/printing_context_win.cc

Index: printing/printing_context_win.cc
diff --git a/printing/printing_context_win.cc b/printing/printing_context_win.cc
index ebe9d183889761e5c1f55e3cb2196d70f49cfb84..99f92cb3be0005305e7b4ea6865b8db8932a16a8 100644
--- a/printing/printing_context_win.cc
+++ b/printing/printing_context_win.cc
@@ -14,6 +14,7 @@
 #include "base/time.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
+#include "base/win/metro.h"
 #include "printing/backend/win_helper.h"
 #include "printing/print_job_constants.h"
 #include "printing/print_settings_initializer_win.h"
@@ -219,6 +220,21 @@ void PrintingContextWin::AskUserForSettings(
     const PrintSettingsCallback& callback) {
 #if !defined(USE_AURA)
   DCHECK(!in_print_job_);
+
+  if (base::win::IsMetroProcess()) {
+    // The system dialog can not be opened while running in Metro.
+    // But we can programatically launch the Metro print device charm though.
+    HMODULE metro_module = base::win::GetMetroModule();
+    if (metro_module != NULL) {
+      typedef void (*MetroShowPrintUI)();

[Albert Bodenhamer, 2012/07/12 16:32:10]

Nit: Is the prototype for MetroShowPrintUI defined in a header somewhere?

Longer term: Does it make sense to build a wrapper class around the the Metro
module that will either delay load or dynamically load the DLL and fail
gracefully?  Exposing all of the dynamic load code in callers adds clutter and
bloat.

[MAD, 2012/07/12 17:16:14]

There's work in progress for this... Not quite ready yet...

+      MetroShowPrintUI metro_show_print_ui =
+          reinterpret_cast<MetroShowPrintUI>(
+              ::GetProcAddress(metro_module, "MetroShowPrintUI"));
+      if (metro_show_print_ui)
+        metro_show_print_ui();
+    }
+    return callback.Run(CANCEL);
+  }
   dialog_box_dismissed_ = false;
 
   HWND window;