Print Preview: Hook up the print button to initiate printing without displaying a print dialog.

chrome/browser/printing/printer_query.cc

Index: chrome/browser/printing/printer_query.cc
diff --git a/chrome/browser/printing/printer_query.cc b/chrome/browser/printing/printer_query.cc
index f39960f89ff0fd2db6c1802881b730a2bcfe29d4..4c25df94ad4166b276e354db5dba9b5d65de61cf 100644
--- a/chrome/browser/printing/printer_query.cc
+++ b/chrome/browser/printing/printer_query.cc
@@ -107,6 +107,32 @@ void PrinterQuery::GetSettings(GetSettingsAskParam ask_user_for_settings,
       use_overlays));
 }
 
+void PrinterQuery::SetSettings(const std::string& new_settings,
+    CancelableTask* callback) {
+  DCHECK(!callback_.get());
+  DCHECK(worker_.get());
+  if (!worker_.get())
+    return;
+
+  // Lazy create the worker thread. There is one worker thread per print job.
+  if (!worker_->message_loop()) {
+    if (!worker_->Start()) {
+      if (callback) {
+        callback->Cancel();
+        delete callback;
+      }
+      NOTREACHED();
+      return;
+    }
+  }
+
+  callback_.reset(callback);
+  worker_->message_loop()->PostTask(FROM_HERE, NewRunnableMethod(
+      worker_.get(),
+      &PrintJobWorker::SetSettings,
+      new_settings));
+}
+
 void PrinterQuery::StopWorker() {
   if (worker_.get()) {
     // http://crbug.com/66082: We're blocking on the PrinterQuery's worker