- 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/osr_util.cc

@@ -0,0 +1,25 @@
+// 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.
+
+#include "libcef/browser/osr/osr_util.h"
+
+namespace osr_util {
+
+namespace {
+
+// The rate at which new calls to OnPaint will be generated.
+const int kDefaultFrameRate = 30;
+const int kMaximumFrameRate = 60;
+
+}  // namespace
+
+int ClampFrameRate(int frame_rate) {
+  if (frame_rate < 1)
+    return kDefaultFrameRate;
+  else if (frame_rate > kMaximumFrameRate)
+    return kMaximumFrameRate;
+  return frame_rate;
+}
+
+}  // namespace osr_util