cc: Add PictureLayerTilingSet to manage PictureLayerTiling

cc/picture_layer_tiling_set_unittest.cc

+// Copyright 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.
+
+#include "cc/picture_layer_tiling_set.h"
+
+#include "cc/test/fake_picture_layer_tiling_client.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/size_conversions.h"
+
+namespace cc {
+
+TEST(PictureLayerTilingSetTest, NoResources) {
+  FakePictureLayerTilingClient client;
+  PictureLayerTilingSet set(&client);
+  gfx::Size default_tile_size(256, 256);
+
+  gfx::Size layer_bounds(1000, 800);
+  set.SetLayerBounds(layer_bounds);
+
+  set.AddTiling(1.0, default_tile_size);
+  set.AddTiling(1.5, default_tile_size);
+  set.AddTiling(2.0, default_tile_size);
+
+  float contents_scale = 2.0;
+  gfx::Size content_bounds(
+      gfx::ToCeiledSize(gfx::ScaleSize(layer_bounds, contents_scale)));
+  gfx::Rect content_rect(gfx::Point(), content_bounds);
+
+  Region remaining(content_rect);
+  PictureLayerTilingSet::Iterator iter(&set, contents_scale, content_rect);
+  for (; iter; ++iter) {
+    gfx::Rect geometry_rect = iter.geometry_rect();
+    EXPECT_TRUE(content_rect.Contains(geometry_rect));
+    ASSERT_TRUE(remaining.Contains(geometry_rect));
+    remaining.Subtract(geometry_rect);
+
+    // No tiles have resources, so no iter represents a real tile.
+    EXPECT_FALSE(*iter);
+  }
+  EXPECT_TRUE(remaining.IsEmpty());
+}
+
+}  // namespace cc