Fix a crash on clicking "Load unpacked extension" multiple times

chrome/browser/ui/webui/extensions/extension_loader_handler.cc

Index: chrome/browser/ui/webui/extensions/extension_loader_handler.cc
diff --git a/chrome/browser/ui/webui/extensions/extension_loader_handler.cc b/chrome/browser/ui/webui/extensions/extension_loader_handler.cc
index bf47de246f8be327b89911bc87f8832bb9da1387..0cf4cc71e1508fc2ed918593a61c6e2bcdc881b7 100644
--- a/chrome/browser/ui/webui/extensions/extension_loader_handler.cc
+++ b/chrome/browser/ui/webui/extensions/extension_loader_handler.cc
@@ -99,11 +99,16 @@ void ExtensionLoaderHandler::FileHelper::ChooseFile() {
   static const ui::SelectFileDialog::Type kSelectType =
       ui::SelectFileDialog::SELECT_FOLDER;
 
+  gfx::NativeWindow parent_window =
+      loader_handler_->web_ui()->GetWebContents()->GetTopLevelNativeWindow();
   if (!load_extension_dialog_.get()) {
     load_extension_dialog_ = ui::SelectFileDialog::Create(
         this,
         new ChromeSelectFilePolicy(
             loader_handler_->web_ui()->GetWebContents()));
+  } else if (load_extension_dialog_->IsRunning(parent_window)) {
+    LOG(ERROR) << "Select file dialog already in use!";

[Devlin, 2014/12/04 21:39:10]

Generally, we don't like to log errors for things that can happen in the normal
course of action.  Since we should be able to handle the user clicking on the
load button twice, I'd remove this in favor of a comment
// File chooser dialog is already running; ignore the click.

+    return;
   }
 
   load_extension_dialog_->SelectFile(
@@ -113,7 +118,7 @@ void ExtensionLoaderHandler::FileHelper::ChooseFile() {
       NULL,
       kFileTypeIndex,
       base::FilePath::StringType(),
-      loader_handler_->web_ui()->GetWebContents()->GetTopLevelNativeWindow(),
+      parent_window,
       NULL);
 
   content::RecordComputedAction("Options_LoadUnpackedExtension");