Make File-Picker modal on Linux

ui/shell_dialogs/select_file_dialog.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_SHELL_DIALOGS_SELECT_FILE_DIALOG_H_
 #define UI_SHELL_DIALOGS_SELECT_FILE_DIALOG_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 152 matching lines @@
   // NOTE: only one instance of any shell dialog can be shown per owning_window
   //       at a time (for obvious reasons).
   void SelectFile(Type type,
                   const base::string16& title,
                   const base::FilePath& default_path,
                   const FileTypeInfo* file_types,
                   int file_type_index,
                   const base::FilePath::StringType& default_extension,
                   gfx::NativeWindow owning_window,
                   void* params);
+  void Close();
   bool HasMultipleFileTypeChoices();
 
   // Sets the global ShellDialogsDelegate. Defaults to NULL.
   static void SetShellDialogsDelegate(ShellDialogsDelegate* delegate);
 
  protected:
   friend class base::RefCountedThreadSafe<SelectFileDialog>;
   explicit SelectFileDialog(Listener* listener, SelectFilePolicy* policy);
   ~SelectFileDialog() override;
 
   // Displays the actual file-selection dialog.
   // This is overridden in the platform-specific descendants of FileSelectDialog
   // and gets called from SelectFile after testing the
   // AllowFileSelectionDialogs-Policy.
   virtual void SelectFileImpl(
       Type type,
       const base::string16& title,
       const base::FilePath& default_path,
       const FileTypeInfo* file_types,
       int file_type_index,
       const base::FilePath::StringType& default_extension,
       gfx::NativeWindow owning_window,
       void* params) = 0;
 
+  virtual void CloseImpl() = 0;

[msw, 2015/09/23 17:12:21]

Give this base class a CloseImpl definition that just calls NOTIMPLEMENTED(), so
each implementation doesn't have to define this.

+
   // Returns the global ShellDialogsDelegate instance if any.
   ShellDialogsDelegate* GetShellDialogsDelegate();
 
   // The listener to be notified of selection completion.
   Listener* listener_;
 
  private:
   // Tests if the file selection dialog can be displayed by
   // testing if the AllowFileSelectionDialogs-Policy is
   // either unset or set to true.
   bool CanOpenSelectFileDialog();
 
   // Informs the |listener_| that the file selection dialog was canceled. Moved
   // to a function for being able to post it to the message loop.
   void CancelFileSelection(void* params);
 
   // Returns true if the dialog has multiple file type choices.
   virtual bool HasMultipleFileTypeChoicesImpl() = 0;
 
   scoped_ptr<SelectFilePolicy> select_file_policy_;
 
   DISALLOW_COPY_AND_ASSIGN(SelectFileDialog);
 };
 
 }  // namespace ui
 
 #endif  // UI_SHELL_DIALOGS_SELECT_FILE_DIALOG_H_