Send compositor frame IPC with metadata.

cc/compositor_frame_metadata.h

Index: cc/compositor_frame_metadata.h
diff --git a/cc/compositor_frame_metadata.h b/cc/compositor_frame_metadata.h
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+// 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 "cc/cc_export.h"
+#include "ui/gfx/size_f.h"
+#include "ui/gfx/vector2d_f.h"
+
+namespace cc {
+
+struct CC_EXPORT CompositorFrameMetadata
+{
+    CompositorFrameMetadata();
+    ~CompositorFrameMetadata();
+
+    // Scroll offset and scale of the root layer. This can be used for tasks
+    // like positioning windowed plugins.
+    gfx::Vector2dF root_scroll_offset;
+    float page_scale_factor;
+
+    // These limits can be used together with the scroll/scale fields above to
+    // determine if scrolling/scaling in a particular direction is possible.
+    gfx::SizeF viewport_size;
+    gfx::SizeF root_layer_size;
+    float min_page_scale_factor;
+    float max_page_scale_factor;
+
+    // Used to position the Android location top bar, whose precise
+    // position is computed by the renderer compositor.
+    gfx::Vector2dF location_bar_offset;
+};
+
+}  // namespace cc
+
+#endif  // CC_COMPOSITOR_FRAME_METADATA_H_