Send compositor frame IPC with metadata.

cc/compositor_frame_metadata.h

+// 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.
+
+#ifndef CC_COMPOSITOR_FRAME_METADATA_H_
+#define CC_COMPOSITOR_FRAME_METADATA_H_
+
+#include "ui/gfx/size_f.h"
+#include "ui/gfx/vector2d_f.h"
+
+namespace cc {
+
+struct CompositorFrameMetadata
+{
+    CompositorFrameMetadata();
+    ~CompositorFrameMetadata();
+
+    // Scroll offset and scale of the root layer. This can be used for tasks
+    // like positioning windowed plugins.
+    gfx::Vector2dF rootScrollOffset;

[danakj, 2012/11/21 03:39:07]

new files in chromium style

+    float pageScaleFactor;
+
+    // These limits can be used together with the scroll/scale fields above to
+    // determine if scrolling/scaling in a particular direction is possible.

[danakj, 2012/11/21 03:39:07]

The browser compositor isn't going to be answering scroll questions though, is
it? I thought we're going to have the renderer deal with scroll.

+    gfx::SizeF viewportSize;
+    gfx::SizeF rootLayerSize;
+    float minPageScaleFactor;
+    float maxPageScaleFactor;
+};
+
+}  // namespace cc
+
+#endif  // CC_COMPOSITOR_FRAME_METADATA_H_