Add support for virtual displays

ui/display/chromeos/display_snapshot_virtual.h

Index: ui/display/chromeos/display_snapshot_virtual.h
diff --git a/ui/display/chromeos/display_snapshot_virtual.h b/ui/display/chromeos/display_snapshot_virtual.h
new file mode 100644
index 0000000000000000000000000000000000000000..8ecd51e8c34b6edda2b35d74f9c4a487828871f5
--- /dev/null
+++ b/ui/display/chromeos/display_snapshot_virtual.h
@@ -0,0 +1,35 @@
+// Copyright 2014 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_DISPLAY_CHROMEOS_DISPLAY_SNAPSHOT_VIRTUAL_H_
+#define UI_DISPLAY_CHROMEOS_DISPLAY_SNAPSHOT_VIRTUAL_H_
+
+#include "ui/display/types/display_snapshot.h"
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/display/types/display_mode.h"
+
+namespace ui {
+
+// This class represents a virtual display to be enabled on demand. The display
+// is constructed for the desired pixel resolution.
+class DisplaySnapshotVirtual : public DisplaySnapshot {
+ public:
+  // |display_id| is the numerical identifier for the virtual display,
+  // |display_size| is the pixel dimensions for the display.
+  DisplaySnapshotVirtual(int64_t display_id, const gfx::Size& display_size);
+  ~DisplaySnapshotVirtual() override;
+
+  // DisplaySnapshot overrides.
+  std::string ToString() const override;
+
+ private:
+  scoped_ptr<DisplayMode> mode_;
+  DISALLOW_COPY_AND_ASSIGN(DisplaySnapshotVirtual);
+};
+
+}  // namespace ui
+
+#endif  // UI_DISPLAY_CHROMEOS_DISPLAY_SNAPSHOT_VIRTUAL_H_