Close web contents modal dialogs on content load start

chrome/browser/ui/tab_modal_confirm_dialog.h

Index: chrome/browser/ui/tab_modal_confirm_dialog.h
diff --git a/chrome/browser/ui/tab_modal_confirm_dialog.h b/chrome/browser/ui/tab_modal_confirm_dialog.h
index 6bd54acc963669644d64093474f34b5cb834a1eb..838e70527b781bf7e786d11ffdd7c0850a7c8909 100644
--- a/chrome/browser/ui/tab_modal_confirm_dialog.h
+++ b/chrome/browser/ui/tab_modal_confirm_dialog.h
@@ -12,7 +12,7 @@ class WebContents;
 }
 
 // Base class for the tab modal confirm dialog.
-class TabModalConfirmDialog : public TabModalConfirmDialogCloseDelegate {
+class TabModalConfirmDialog : public TabModalConfirmDialogOperationsDelegate {
  public:
   // Platform specific factory function. This function will automatically show
   // the dialog.
@@ -24,9 +24,11 @@ class TabModalConfirmDialog : public TabModalConfirmDialogCloseDelegate {
   // Cancels the dialog.
   virtual void CancelTabModalDialog() = 0;
 
-  // TabModalConfirmDialogCloseDelegate:
+  // TabModalConfirmDialogOperationsDelegate:
   // Closes the dialog.
   virtual void CloseDialog() = 0;
+  // Prevents the dialog from closing on WebContents load start.
+  virtual void SetPreventCloseOnLoadStart(bool prevent) = 0;
 
  protected:
   virtual ~TabModalConfirmDialog() {}