Add sign in dialog for GCP->print preview integration.

chrome/browser/ui/webui/print_preview_handler.cc

Index: chrome/browser/ui/webui/print_preview_handler.cc
diff --git a/chrome/browser/ui/webui/print_preview_handler.cc b/chrome/browser/ui/webui/print_preview_handler.cc
index aa0007fd5fa919b5b22a0984bd0177bf1219d5dd..56fd324bd69dc666711aa51cfb5e85f8c354f8c8 100644
--- a/chrome/browser/ui/webui/print_preview_handler.cc
+++ b/chrome/browser/ui/webui/print_preview_handler.cc
@@ -29,6 +29,7 @@
 #include "chrome/browser/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/tab_contents/tab_contents_wrapper.h"
+#include "chrome/browser/ui/webui/cloud_print_signin_dialog.h"
 #include "chrome/browser/ui/webui/print_preview_ui.h"
 #include "chrome/common/chrome_paths.h"
 #if !defined(OS_CHROMEOS)
@@ -426,7 +427,7 @@ void PrintPreviewHandler::RegisterMessages() {
   web_ui_->RegisterMessageCallback("morePrinters",
       NewCallback(this, &PrintPreviewHandler::HandleShowSystemDialog));
   web_ui_->RegisterMessageCallback("signIn",
-      NewCallback(this, &PrintPreviewHandler::HandleManageCloudPrint));
+      NewCallback(this, &PrintPreviewHandler::HandleSignin));
   web_ui_->RegisterMessageCallback("addCloudPrinter",
       NewCallback(this, &PrintPreviewHandler::HandleManageCloudPrint));
   web_ui_->RegisterMessageCallback("manageCloudPrinters",
@@ -653,6 +654,10 @@ void PrintPreviewHandler::HandleGetPrinterCapabilities(
                         printer_name));
 }
 
+void PrintPreviewHandler::HandleSignin(const ListValue*) {
+  cloud_print_signin_dialog::CreateCloudPrintSigninDialog(preview_tab());
+}
+
 void PrintPreviewHandler::HandleManageCloudPrint(const ListValue*) {
   Browser* browser = BrowserList::GetLastActive();
   browser->OpenURL(CloudPrintURL(browser->profile()).