Add support for a virtual display on ChromeOS

ui/display/chromeos/display_snapshot_virtual.cc

+// 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.
+
+#include "ui/display/chromeos/display_snapshot_virtual.h"
+
+#include "base/strings/stringprintf.h"
+#include "ui/display/types/display_mode.h"
+
+namespace ui {
+DisplaySnapshotVirtual::DisplaySnapshotVirtual(uint32_t index,
+                                               DisplayMode* mode)
+    : DisplaySnapshot(index,
+                      gfx::Point(0, 0),
+                      gfx::Size(200, 200),

[Daniel Erat, 2015/02/23 23:14:53]

where do these numbers come from?

(i have flashbacks of 200x200 dimensions from excessive gtk+ programming in the
past)

[dnicoara, 2015/02/24 16:27:06]

This would be the physical size of the display. We may want to have something
smarter here since Ash uses this and the resolution to compute the DPI.

Or at least have a TODO to revisit this.

[robert.bradford, 2015/03/03 19:58:00]

I've put a TODO in here for now but would love to hear thoughts on how we could
improve this or maybe just tweak the constants.

+                      DISPLAY_CONNECTION_TYPE_VIRTUAL,
+                      false,
+                      false,
+                      "Virtual output",
+                      std::vector<const DisplayMode*>(),
+                      NULL,
+                      NULL) {
+  modes_.push_back(new DisplayMode(mode->size(), mode->is_interlaced(),

[dnicoara, 2015/02/24 16:27:06]

This mode is leaking.

[robert.bradford, 2015/03/03 19:58:00]

Fixed by adding a scoped_ptr member to store the internal mode after contruction
via a gfx::Size.

+                                   mode->refresh_rate()));
+
+  native_mode_ = modes_.front();
+}
+
+DisplaySnapshotVirtual::~DisplaySnapshotVirtual() {
+}
+
+std::string DisplaySnapshotVirtual::ToString() const {
+  return base::StringPrintf(
+      "Virtual %s %s",
+      current_mode_ ? current_mode_->ToString().c_str() : "NULL",
+      physical_size_.ToString().c_str());
+}
+
+}  // namespace ui