Make cc/paint have concrete types

cc/paint/paint_surface.cc

Index: cc/paint/paint_surface.cc
diff --git a/cc/paint/paint_surface.cc b/cc/paint/paint_surface.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a46220ebafd7e120d1e5ca42169e389c3dab58bf
--- /dev/null
+++ b/cc/paint/paint_surface.cc
@@ -0,0 +1,14 @@
+// Copyright 2017 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 "cc/paint/paint_surface.h"
+
+namespace cc {
+
+PaintSurface::PaintSurface(sk_sp<SkSurface> surface)
+    : surface_(std::move(surface)) {}
+
+PaintSurface::~PaintSurface() = default;
+
+}  // namespace cc