Reworked the plumbing required to pass the client resolution to the desktop resizer.

remoting/host/screen_resolution.cc

+// Copyright (c) 2013 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 "remoting/host/screen_resolution.h"
+
+#include <algorithm>
+#include <limits>
+
+// Default dots per inch is 96 DPI.

[Jamie, 2013/03/15 18:33:24]

I think the default DPI on Mac is 72, but we ignore that. It might be worth a
comment here; talk to Wez about it.

[alexeypa (please no reviews), 2013/03/15 20:30:41]

Talked to Wez. He said it is better to have this class to always specify DPI.
Done.

+const int kDefaultDpiX = 96;
+const int kDefaultDpiY = 96;
+
+namespace remoting {
+
+ScreenResolution::ScreenResolution()
+    : dimensions_(SkISize::Make(0, 0)),
+      dpi_(SkIPoint::Make(0, 0)) {
+}
+
+ScreenResolution::ScreenResolution(const SkISize& dimensions)
+    : dimensions_(dimensions),
+      dpi_(SkIPoint::Make(0, 0)) {
+}
+
+SkIPoint ScreenResolution::GetEffectiveDpi() const {
+  SkIPoint dpi = dpi_;
+  if (!dpi.x())
+    dpi.setX(kDefaultDpiX);
+  if (!dpi.y())
+    dpi.setY(kDefaultDpiY);
+  return dpi;
+}
+
+SkISize ScreenResolution::GetLogicalDimensions() const {
+  SkIPoint dpi = GetEffectiveDpi();
+
+  // Make sure there will be no integer overflow while scaling the screen
+  // dimensions.
+  SkISize dimensions = SkISize::Make(
+      std::min(dimensions_.width(),
+               std::numeric_limits<int32_t>::max() / kDefaultDpiX),
+      std::min(dimensions_.height(),
+               std::numeric_limits<int32_t>::max() / kDefaultDpiY));
+
+  // Scale the screen dimensions as if DPI was 96.
+  return SkISize::Make(dimensions.width() * kDefaultDpiX / dpi.x(),
+                       dimensions.height() * kDefaultDpiY / dpi.y());
+}
+
+bool ScreenResolution::IsNull() const {
+  return !IsValid() || dimensions_.isZero();
+}
+
+bool ScreenResolution::IsValid() const {
+  return dimensions_.width() >= 0 && dimensions_.height() >= 0 &&
+      dpi_.x() >= 0 && dpi_.y() >= 0;
+}
+
+}  // namespace remoting