Don't allow more than one pending print dialog per browser instance.

As a future TODO, it might be nice to limit it per-tab instead of per-app.

BUG=46575
TEST=manual

Review URL: http://codereview.chromium.org/2848011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@50203 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 30 insertions, 1 deletions

diff --git a/chrome/browser/printing/print_dialog_gtk.cc b/chrome/browser/printing/print_dialog_gtk.cc
index 1428ed7..5cc203d 100644
--- a/chrome/browser/printing/print_dialog_gtk.cc
+++ b/chrome/browser/printing/print_dialog_gtk.cc
@@ -9,6 +9,8 @@
 #include <gtk/gtkpagesetupunixdialog.h>
 
 #include "base/file_util.h"
+#include "base/lazy_instance.h"
+#include "base/lock.h"
 #include "base/logging.h"
 #include "chrome/browser/browser_list.h"
 #include "chrome/browser/browser_window.h"
@@ -18,6 +20,14 @@
 
 namespace {
 
+PrintDialogGtk* g_print_dialog = NULL;
+
+// Used to make accesses to the above thread safe.
+Lock& DialogLock() {
+  static base::LazyInstance<Lock> dialog_lock(base::LINKER_INITIALIZED);
+  return dialog_lock.Get();
+}
+
 // This is a temporary infobar designed to help gauge how many users are trying
 // to print to printers that don't support PDF.
 class PdfUnsupportedInfoBarDelegate : public LinkInfoBarDelegate {
@@ -65,8 +75,22 @@ void PrintDialogGtk::CreatePrintDialogForPdf(const FilePath& path) {
 }
 
 // static
+bool PrintDialogGtk::DialogShowing() {
+  AutoLock lock(DialogLock());
+  return !!g_print_dialog;
+}
+
+// static
 void PrintDialogGtk::CreateDialogImpl(const FilePath& path) {
-  new PrintDialogGtk(path);
+  // Only show one print dialog at once. This is to prevent a page from
+  // locking up the system with
+  //
+  //   while(true){print();}
+  AutoLock lock(DialogLock());
+  if (g_print_dialog)
+    return;
+
+  g_print_dialog = new PrintDialogGtk(path);
 }
 
 PrintDialogGtk::PrintDialogGtk(const FilePath& path_to_pdf)
@@ -82,6 +106,9 @@ PrintDialogGtk::PrintDialogGtk(const FilePath& path_to_pdf)
 }
 
 PrintDialogGtk::~PrintDialogGtk() {
+  AutoLock lock(DialogLock());
+  DCHECK_EQ(this, g_print_dialog);
+  g_print_dialog = NULL;
 }
 
 void PrintDialogGtk::OnResponse(gint response_id) {
diff --git a/chrome/browser/printing/print_dialog_gtk.h b/chrome/browser/printing/print_dialog_gtk.h
index 589af80..0c1087f 100644
--- a/chrome/browser/printing/print_dialog_gtk.h
+++ b/chrome/browser/printing/print_dialog_gtk.h
@@ -17,6 +17,8 @@ typedef struct _GtkPrintJob GtkPrintJob;
 // Currently this dialog only allows the user to choose a printer.
 class PrintDialogGtk {
  public:
+  static bool DialogShowing();
+
   // Called on the IO thread.
   static void CreatePrintDialogForPdf(const FilePath& path);