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

remoting/host/screen_resolution.h

+// 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.
+
+#ifndef REMOTING_HOST_SCREEN_RESOLUTION_H_
+#define REMOTING_HOST_SCREEN_RESOLUTION_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "third_party/skia/include/core/SkPoint.h"
+#include "third_party/skia/include/core/SkSize.h"
+
+namespace remoting {
+
+// This structure describes the screen's dimensions and DPI.
+struct ScreenResolution {
+  ScreenResolution();
+
+  // Initializes |this| assuming the efault DPI.
+  explicit ScreenResolution(const SkISize& dimensions);
+
+  // Returns the default DPI of (96, 96) if |dpi_| is (0, 0). Returns |dpi_|
+  // otherwise.
+  SkIPoint GetEffectiveDpi() const;
+
+  // Returns the screen dimensions in logical pixels. I.e. returns
+  // the dimensions of a screen of the same size displaying 96 pixels per inch.
+  SkISize GetLogicalDimensions() const;
+
+  // Returns true if either the screen size is empty or IsValid() returns false.
+  bool IsNull() const;
+
+  // Returns true if both |dimensions_| and |dpi_| are non-negative.
+  bool IsValid() const;

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

I think it's worth doing a careful audit (perhaps in a separate CL) to determine
whether or not we really need both of these methods.

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

We need both. We need to be able to check if the structure is valid (obviously).
There are two valid states:

- |dimensions_| is an empty rectangle. I.e. the caller does not specify what the
resolution should be. 
- |dimensions_| is a non-empty rectangle. In this case the caller knows the
exact resolution.

An example when the "empty rectangle" state is needed: when a client connects
its resolution is not yet knows, but we need to create a session already.

[Jamie, 2013/03/15 22:06:27]

Fair enough; thanks for the clarification. However, I'd suggest calling it
IsEmpty instead of IsNull, since null has  a specific meaning in other contexts
that's not appropriate here.

[alexeypa (please no reviews), 2013/03/15 22:32:12]

Done.

+
+  // Dimensions of the screen in pixels.
+  SkISize dimensions_;
+
+  // The vertical and horizontal DPI of the screen.
+  SkIPoint dpi_;
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_SCREEN_RESOLUTION_H_