Refactor screen/monitor so that gfx::Screen returns monitor object.

ui/gfx/monitor.cc

+// Copyright (c) 2012 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/gfx/monitor.h"
+
+#include "ui/gfx/insets.h"
+
+namespace gfx {
+
+Monitor::Monitor() : device_scale_factor_(1.0) {
+}
+
+Monitor::Monitor(const gfx::Rect& bounds)
+    : bounds_(bounds), work_area_(bounds), device_scale_factor_(1.0) {
+}
+
+Monitor::~Monitor() {
+}
+
+void Monitor::SetBoundsAndUpdateWorkArea(const gfx::Rect& bounds) {
+  Insets insets(work_area_.y() - bounds_.y(),
+                work_area_.x() - bounds_.x(),
+                bounds_.bottom() - work_area_.bottom(),
+                bounds_.right() - work_area_.right());
+  bounds_ = bounds;
+  UpdateWorkAreaWithInsets(insets);
+}
+
+void Monitor::SetSizeAndUpdateWorkArea(const gfx::Size& size) {
+  SetBoundsAndUpdateWorkArea(gfx::Rect(bounds_.origin(), size));
+}
+
+void Monitor::UpdateWorkAreaWithInsets(const gfx::Insets& insets) {
+  work_area_ = bounds_;
+  work_area_.Inset(insets);
+}
+
+}  // namespace gfx