Process DisplaySnapshots in PlatformScreen.

ui/display/chromeos/display_snapshot_virtual.h

 // 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 <stdint.h>
 
 #include <memory>
 
 #include "base/macros.h"
+#include "ui/display/display_export.h"
 #include "ui/display/types/display_mode.h"
 #include "ui/display/types/display_snapshot.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 {
+class DISPLAY_EXPORT 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:
   std::unique_ptr<DisplayMode> mode_;
   DISALLOW_COPY_AND_ASSIGN(DisplaySnapshotVirtual);
 };
 
 }  // namespace ui
 
 #endif  // UI_DISPLAY_CHROMEOS_DISPLAY_SNAPSHOT_VIRTUAL_H_