POSIX: gfx::NativeViewId and CrossProcessEvent

base/gfx/native_widget_types.h

 // Copyright (c) 2008 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 BASE_GFX_NATIVE_WIDGET_TYPES_H_
 #define BASE_GFX_NATIVE_WIDGET_TYPES_H_
 
+#include "base/basictypes.h"
 #include "build/build_config.h"
 
 // This file provides cross platform typedefs for native widget types.
 //   NativeWindow: this is a handle to a native, top-level window
 //   NativeView: this is a handle to a native UI element. It may be the
 //     same type as a NativeWindow on some platforms.
-//   NativeEditView: a handle to a native edit-box. The Mac folks wanted
-//     this specific typedef.
+//   NativeViewId: Often, in our cross process model, we need to pass around a
+//     reference to a "window". This reference will, say, be echoed back from a
+//     renderer to the browser when it wishes to query it's size. On Windows, a
+//     HWND can be used for this. On other platforms, we may wish to pass
+//     around X window ids, or maybe abstract identifiers.
+//
+//     As a rule of thumb - if you're in the renderer, you should be dealing
+//     with NativeViewIds. This should remind you that you shouldn't be doing
+//     direct operations on platform widgets from the renderer process.
+//
+//     If you're in the browser, you're probably dealing with NativeViews,
+//     unless you're in the IPC layer, which will be translating between
+//     NativeViewIds from the renderer and NativeViews.
+//
+//   NativeEditView: a handle to a native edit-box. The Mac folks wanted this
+//     specific typedef.
 //
 // The name 'View' here meshes with OS X where the UI elements are called
 // 'views' and with our Chrome UI code where the elements are also called
 // 'views'.
 
 #if defined(OS_WIN)
 #include <windows.h>
 #elif defined(OS_MACOSX)
 #ifdef __OBJC__
 @class NSView;
@@ skipping 19 matching lines @@
 typedef NSWindow* NativeWindow;
 typedef NSTextField* NativeEditView;
 #elif defined(OS_LINUX)
 typedef GtkWidget* NativeView;
 typedef GtkWidget* NativeWindow;
 typedef GtkWidget* NativeEditView;
 #else  // null port.
 #error No known OS defined
 #endif
 
+// Note: for test_shell we're packing a pointer into the NativeViewId. So, if
+// you make it a type which is smaller than a pointer, you have to fix
+// test_shell.
+//
+// See comment at the top of the file for usage.
+typedef intptr_t NativeViewId;
+
+// Convert a NativeViewId to a NativeView. At the moment, we assume that the
+// ids are the same as the NativeViews. This is correct on Windows (where
+// NativeView == HWND).
+// TODO(port): figure out what ids are going to be and implement this function
+// This is only to be called in the browser process.
+static inline NativeView NativeViewFromId(NativeViewId id) {
+  return reinterpret_cast<NativeView>(id);
+}
+
+// Convert a NativeView to a NativeViewId. At the moment, we assume that the
+// ids are the same as the NativeViews. This is correct on Windows (where
+// NativeView == HWND).
+// TODO(port): figure out what ids are going to be and implement this function
+// This is only to be called in the browser process.
+static inline NativeViewId IdFromNativeView(NativeView view) {
+  return reinterpret_cast<NativeViewId>(view);
+}
+
 }  // namespace gfx
 
 #endif  // BASE_GFX_NATIVE_WIDGET_TYPES_H_