ozone: Introduce ClientPixmap and ClientPixmapFactory for non-GPU processes.

ui/ozone/common/stub_native_pixmap_manager.cc

+// Copyright 2015 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.
+
+#include "ui/ozone/common/stub_native_pixmap_manager.h"
+
+namespace ui {
+
+namespace {
+
+class StubNativePixmapManager : public NativePixmapManager {
+ public:
+  StubNativePixmapManager() {}
+  ~StubNativePixmapManager() override {}
+
+  std::vector<Configuration> GetSupportedNativePixmapConfigurations()
+      const override {
+    return std::vector<Configuration>();
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(StubNativePixmapManager);
+};
+
+}  // namespace
+
+NativePixmapManager* CreateStubNativePixmapManager() {
+  return new StubNativePixmapManager;
+}
+
+}  // namespace ui