Merge 50561 - Fix a crash when we try to close a js dialog that wasn't shown....

chrome/browser/js_modal_dialog.cc

Index: chrome/browser/js_modal_dialog.cc
===================================================================
--- chrome/browser/js_modal_dialog.cc	(revision 51020)
+++ chrome/browser/js_modal_dialog.cc	(working copy)
@@ -20,6 +20,9 @@
     bool is_before_unload_dialog,
     IPC::Message* reply_msg)
     : AppModalDialog(client->AsTabContents(), title),
+#if defined(OS_MACOSX)
+      dialog_(NULL),
+#endif
       client_(client),
       extension_host_(client->AsExtensionHost()),
       dialog_flags_(dialog_flags),
@@ -51,7 +54,8 @@
   // Also clear the client, since it's now invalid.
   skip_this_dialog_ = true;
   client_ = NULL;
-  CloseModalDialog();
+  if (dialog_)
+    CloseModalDialog();
 }
 
 void JavaScriptAppModalDialog::InitNotifications() {
@@ -123,4 +127,3 @@
   }
   AppModalDialog::Cleanup();
 }
-