- Factor platform-specific code out of CefBrowserHostImpl (issue #1749).

- Introduce native/ and osr/ folders for native (non-platform-agnostic) and
    osr (windowless) code respectively.
  - Introduce CefBrowserPlatformDelegate for abstracting platform-specific
    implementations of browser host functionality.
  - Move dialog and menu code to separate manager and platform-specific runner
    implementations exposed via CefBrowserPlatformDelegate.
  - Standardize focus-handling behavior between windowed and windowless
    implementations. CefFocusHandler::OnSetFocus() will now also be called for
    osr focus changes.
- Support multiple simultaneous popups (issue #1289).

libcef/browser/osr/browser_platform_delegate_osr_linux.h

@@ -0,0 +1,21 @@
+// Copyright 2015 The Chromium Embedded Framework 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 CEF_LIBCEF_BROWSER_OSR_BROWSER_PLATFORM_DELEGATE_OSR_LINUX_H_
+#define CEF_LIBCEF_BROWSER_OSR_BROWSER_PLATFORM_DELEGATE_OSR_LINUX_H_
+
+#include "libcef/browser/osr/browser_platform_delegate_osr.h"
+
+// Windowless browser implementation for Linux.
+class CefBrowserPlatformDelegateOsrLinux :
+    public CefBrowserPlatformDelegateOsr {
+ public:
+  explicit CefBrowserPlatformDelegateOsrLinux(
+      scoped_ptr<CefBrowserPlatformDelegateNative> native_delegate);
+
+  // CefBrowserPlatformDelegate methods:
+  CefWindowHandle GetHostWindowHandle() const override;
+};
+
+#endif  // CEF_LIBCEF_BROWSER_NATIVE_BROWSER_PLATFORM_DELEGATE_OSR_LINUX_H_