Register and select printer on click.

chrome/browser/ui/webui/print_preview/printer_backend_proxy.h

Index: chrome/browser/ui/webui/print_preview/printer_backend_proxy.h
diff --git a/chrome/browser/ui/webui/print_preview/printer_backend_proxy.h b/chrome/browser/ui/webui/print_preview/printer_backend_proxy.h
index e950b60163c889e5000b1c5296512fbcb2982a97..eb12570f8cde552cc92557d3aabddf491353a0e2 100644
--- a/chrome/browser/ui/webui/print_preview/printer_backend_proxy.h
+++ b/chrome/browser/ui/webui/print_preview/printer_backend_proxy.h
@@ -8,6 +8,7 @@
 #include <memory>
 #include <string>
 
+#include "base/callback_forward.h"
 #include "base/values.h"
 #include "printing/backend/print_backend.h"
 
@@ -15,12 +16,22 @@ class Profile;
 
 namespace printing {
 
+using PrinterSetupCallback =
+    base::Callback<void(std::unique_ptr<base::DictionaryValue>)>;
+
 // Returns the name of the default printer.
 std::string GetDefaultPrinterOnBlockingPoolThread();
 
 // Returns printers for display in the print dialog.
 PrinterList EnumeratePrintersOnBlockingPoolThread(Profile* profile);
 
+// Verifies printer setup then retrieves printer capabilities for

[Lei Zhang, 2016/11/03 23:41:46]

Maybe say "Verifies printer setup if needed ..." since on non-ChromeOS, there's
no set up happening.

[skau, 2016/11/04 19:28:59]

Done.

+// |printer_name|.  |cb| is called with the capabilities dictionary or nullptr
+// if one of the steps failed.
+void ConfigurePrinterAndFetchCapabilities(Profile* profile,
+                                          const std::string& printer_name,
+                                          const PrinterSetupCallback& cb);
+
 }  // namespace printing
 
 #endif  // CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINTER_BACKEND_PROXY_H_