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

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 65a39edfb37b4e25457a006df08fbb9f6e735eb6..946c93b9a30182af5549f08b590f973ef644261c 100644
--- a/chrome/browser/ui/webui/print_preview_handler.cc
+++ b/chrome/browser/ui/webui/print_preview_handler.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/ui/webui/print_preview_handler.h"
 
+#include "base/json/json_reader.h"
 #include "base/values.h"
 #include "chrome/browser/renderer_host/render_view_host.h"
 #include "printing/backend/print_backend.h"
@@ -35,6 +36,18 @@ void PrintPreviewHandler::HandleGetPrinters(const ListValue*) {
   web_ui_->CallJavascriptFunction(L"setPrinters", printers);
 }
 
-void PrintPreviewHandler::HandlePrint(const ListValue*) {
-  web_ui_->GetRenderViewHost()->PrintForPrintPreview();
+void PrintPreviewHandler::HandlePrint(const ListValue* args) {
+  std::string json_str;
+  CHECK(args->GetString(0, &json_str)) << "Could not read JSON argument";

[Lei Zhang, 2011/03/02 23:28:54]

I would not do a CHECK here. This would imply if the renderer process send us a
bad message, then the browser process would crash! Same for the CHECKs below.
You should not be sprinkling CHECKs in your code so liberally.

[kmadhusu, 2011/03/04 19:39:02]

Fixed.

+  if (json_str.empty()) {
+    NOTREACHED() << "Empty print job settings";
+    return;
+  }
+  scoped_ptr<DictionaryValue> settings(static_cast<DictionaryValue*>(
+          base::JSONReader::Read(json_str, false)));
+  CHECK(settings.get() && settings->IsType(Value::TYPE_DICTIONARY))
+      << "Print job settings must be a dictionary.";
+
+  CHECK(!settings->empty()) << "Print job settings dictionary is empty";
+  web_ui_->GetRenderViewHost()->PrintForPrintPreview(*settings);
 }