cc: Detach spiral iterator implementation to separate file.

cc/base/spiral_iterator_unittest.cc

+// Copyright 2016 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 <stddef.h>
+
+#include <algorithm>
+#include <vector>
+
+#include "cc/base/tiling_data.h"
+#include "cc/test/geometry_test_utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+namespace {
+
+void TestSpiralIterate(int source_line_number,
+                       const TilingData& tiling_data,
+                       const gfx::Rect& consider,
+                       const gfx::Rect& ignore,
+                       const gfx::Rect& center,
+                       const std::vector<std::pair<int, int>>& expected) {
+  std::vector<std::pair<int, int>> actual_forward;
+  for (TilingData::SpiralDifferenceIterator it(&tiling_data, consider, ignore,
+                                               center);
+       it; ++it) {
+    actual_forward.push_back(it.index());
+  }
+
+  EXPECT_EQ(expected.size(), actual_forward.size()) << "error from line "
+                                                    << source_line_number;
+  for (size_t i = 0; i < std::min(expected.size(), actual_forward.size());
+       ++i) {
+    EXPECT_EQ(expected[i].first, actual_forward[i].first)
+        << "i: " << i << " error from line: " << source_line_number;
+    EXPECT_EQ(expected[i].second, actual_forward[i].second)
+        << "i: " << i << " error from line: " << source_line_number;
+  }
+
+  std::vector<std::pair<int, int>> actual_reverse;
+  for (TilingData::ReverseSpiralDifferenceIterator it(&tiling_data, consider,
+                                                      ignore, center);
+       it; ++it) {
+    actual_reverse.push_back(it.index());
+  }
+
+  std::vector<std::pair<int, int>> reversed_expected = expected;
+  std::reverse(reversed_expected.begin(), reversed_expected.end());
+  EXPECT_EQ(reversed_expected.size(), actual_reverse.size())
+      << "error from line " << source_line_number;
+  for (size_t i = 0;
+       i < std::min(reversed_expected.size(), actual_reverse.size()); ++i) {
+    EXPECT_EQ(reversed_expected[i].first, actual_reverse[i].first)
+        << "i: " << i << " error from line: " << source_line_number;
+    EXPECT_EQ(reversed_expected[i].second, actual_reverse[i].second)
+        << "i: " << i << " error from line: " << source_line_number;
+  }
+}
+
+TEST(SpiralIteratorTest, NoIgnoreFullConsider) {

[prashant.n, 2016/09/23 12:11:24]

How about moving this test code under function ExecuteNoIgnoreFullConsider() and
move it to separate file - something like cc\test\SpiralIteratorTest.h; IF WE
WANT THE PERF TESTS FOR SPIRAL ITERATOR.

1. In spiral_iterator_unittest.cc just call the function.

TEST(SpiralIteratorTest, NoIgnoreFullConsider) {
  ExecuteNoIgnoreFullConsider()
}

2. Add the spiral_iterator_perftest.cc and call above function to measure the
perfs.

Do let me know your opinion.

[prashant.n, 2016/09/23 13:52:17]

I thought over this again. I guess we may not need a perf test for spiral
iterator. For algorithm comparison (spiral vs. pyramid) we can local patch and
test the performance difference.

Kindly ignore above comment.

[vmpstr, 2016/09/23 21:05:34]

Yeah I think we can just write a separate perftest, it's not really work sharing
the code between unittests and perftests.

+  TilingData tiling_data(gfx::Size(10, 10), gfx::Size(30, 30), false);
+  gfx::Rect consider(30, 30);
+  gfx::Rect ignore;
+  std::vector<std::pair<int, int>> expected;
+
+  // Center is in the center of the tiling.
+  gfx::Rect center(15, 15, 1, 1);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  4│  3│  2│
+  //    ├───┼───┼───┤
+  //  1 │  5│  *│  1│
+  //    ├───┼───┼───┤
+  //  2 │  6│  7│  8│
+  //    └───┴───┴───┘
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(2, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Center is off to the right side of the tiling (and far away).
+  center = gfx::Rect(100, 15, 1, 1);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  7│  4│  1│
+  //    ├───┼───┼───┤
+  //  1 │  8│  5│  2│    *
+  //    ├───┼───┼───┤
+  //  2 │  9│  6│  3│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 2));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Center is the bottom right corner of the tiling.
+  center = gfx::Rect(25, 25, 1, 1);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  6│  5│  4│
+  //    ├───┼───┼───┤
+  //  1 │  7│  2│  1│
+  //    ├───┼───┼───┤
+  //  2 │  8│  3│  *│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Center is off the top left side of the tiling.
+  center = gfx::Rect(-60, -50, 1, 1);
+
+  // Layout of the tiling data, and expected return order:
+  //  * x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  1│  2│  6│
+  //    ├───┼───┼───┤
+  //  1 │  3│  4│  5│
+  //    ├───┼───┼───┤
+  //  2 │  7│  8│  9│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(2, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Two tile center.
+  center = gfx::Rect(15, 15, 1, 10);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  5│  4│  3│
+  //    ├───┼───┼───┤
+  //  1 │  6│  *│  2│
+  //    ├───┼───┼───┤
+  //  2 │  7│  *│  1│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(2, 2));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+}
+
+TEST(SpiralIteratorTest, SmallConsider) {
+  TilingData tiling_data(gfx::Size(10, 10), gfx::Size(50, 50), false);
+  gfx::Rect ignore;
+  std::vector<std::pair<int, int>> expected;
+  gfx::Rect center(15, 15, 1, 1);
+
+  // Consider is one cell.
+  gfx::Rect consider(1, 1);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │  1│   │   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │   │  *│   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │   │   │   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │   │   │   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │   │   │   │   │   │
+  //    └───┴───┴───┴───┴───┘
+  expected.push_back(std::make_pair(0, 0));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Consider is bottom right corner.
+  consider = gfx::Rect(25, 25, 10, 10);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │   │   │   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │   │  *│   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │   │   │  1│  2│   │
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │   │   │  3│  4│   │
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │   │   │   │   │   │
+  //    └───┴───┴───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(2, 2));
+  expected.push_back(std::make_pair(3, 2));
+  expected.push_back(std::make_pair(2, 3));
+  expected.push_back(std::make_pair(3, 3));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Consider is one column.
+  consider = gfx::Rect(11, 0, 1, 100);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │   │  2│   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │   │  *│   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │   │  3│   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │   │  4│   │   │   │
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │   │  5│   │   │   │
+  //    └───┴───┴───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(1, 3));
+  expected.push_back(std::make_pair(1, 4));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+}
+
+TEST(SpiralIteratorTest, HasIgnore) {
+  TilingData tiling_data(gfx::Size(10, 10), gfx::Size(50, 50), false);
+  gfx::Rect consider(50, 50);
+  std::vector<std::pair<int, int>> expected;
+  gfx::Rect center(15, 15, 1, 1);
+
+  // Full ignore.
+  gfx::Rect ignore(50, 50);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │  I│  I│  I│  I│  I│
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │  I│  *│  I│  I│  I│
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │  I│  I│  I│  I│  I│
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │  I│  I│  I│  I│  I│
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │  I│  I│  I│  I│  I│
+  //    └───┴───┴───┴───┴───┘
+  expected.clear();
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // 3 column ignore.
+  ignore = gfx::Rect(15, 0, 20, 100);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │  1│  I│  I│  I│  8│
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │  2│  *│  I│  I│  7│
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │  3│  I│  I│  I│  6│
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │  4│  I│  I│  I│  5│
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │  9│  I│  I│  I│ 10│
+  //    └───┴───┴───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(0, 3));
+  expected.push_back(std::make_pair(4, 3));
+  expected.push_back(std::make_pair(4, 2));
+  expected.push_back(std::make_pair(4, 1));
+  expected.push_back(std::make_pair(4, 0));
+  expected.push_back(std::make_pair(0, 4));
+  expected.push_back(std::make_pair(4, 4));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Ignore covers the top half.
+  ignore = gfx::Rect(50, 25);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │  I│  I│  I│  I│  I│
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │  I│  *│  I│  I│  I│
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │  I│  I│  I│  I│  I│
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │  1│  2│  3│  4│  5│
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │  6│  7│  8│  9│ 10│
+  //    └───┴───┴───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(0, 3));
+  expected.push_back(std::make_pair(1, 3));
+  expected.push_back(std::make_pair(2, 3));
+  expected.push_back(std::make_pair(3, 3));
+  expected.push_back(std::make_pair(4, 3));
+  expected.push_back(std::make_pair(0, 4));
+  expected.push_back(std::make_pair(1, 4));
+  expected.push_back(std::make_pair(2, 4));
+  expected.push_back(std::make_pair(3, 4));
+  expected.push_back(std::make_pair(4, 4));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+}
+
+TEST(SpiralIteratorTest, RectangleCenter) {
+  TilingData tiling_data(gfx::Size(10, 10), gfx::Size(50, 50), false);
+  gfx::Rect consider(50, 50);
+  std::vector<std::pair<int, int>> expected;
+  gfx::Rect ignore;
+
+  // Two cell center
+  gfx::Rect center(25, 25, 1, 10);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │ 19│ 18│ 17│ 16│ 15│
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │ 20│  5│  4│  3│ 14│
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │ 21│  6│  *│  2│ 13│
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │ 22│  7│  *│  1│ 12│
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │ 23│  8│  9│ 10│ 11│
+  //    └───┴───┴───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(3, 3));
+  expected.push_back(std::make_pair(3, 2));
+  expected.push_back(std::make_pair(3, 1));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(1, 3));
+  expected.push_back(std::make_pair(1, 4));
+  expected.push_back(std::make_pair(2, 4));
+  expected.push_back(std::make_pair(3, 4));
+  expected.push_back(std::make_pair(4, 4));
+  expected.push_back(std::make_pair(4, 3));
+  expected.push_back(std::make_pair(4, 2));
+  expected.push_back(std::make_pair(4, 1));
+  expected.push_back(std::make_pair(4, 0));
+  expected.push_back(std::make_pair(3, 0));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(0, 3));
+  expected.push_back(std::make_pair(0, 4));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Three by two center.
+  center = gfx::Rect(15, 25, 20, 10);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2   3   4
+  //  y ┌───┬───┬───┬───┬───┐
+  //  0 │ 19│ 18│ 17│ 16│ 15│
+  //    ├───┼───┼───┼───┼───┤
+  //  1 │  7│  6│  5│  4│  3│
+  //    ├───┼───┼───┼───┼───┤
+  //  2 │  8│  *│  *│  *│  2│
+  //    ├───┼───┼───┼───┼───┤
+  //  3 │  9│  *│  *│  *│  1│
+  //    ├───┼───┼───┼───┼───┤
+  //  4 │ 10│ 11│ 12│ 13│ 14│
+  //    └───┴───┴───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(4, 3));
+  expected.push_back(std::make_pair(4, 2));
+  expected.push_back(std::make_pair(4, 1));
+  expected.push_back(std::make_pair(3, 1));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(0, 3));
+  expected.push_back(std::make_pair(0, 4));
+  expected.push_back(std::make_pair(1, 4));
+  expected.push_back(std::make_pair(2, 4));
+  expected.push_back(std::make_pair(3, 4));
+  expected.push_back(std::make_pair(4, 4));
+  expected.push_back(std::make_pair(4, 0));
+  expected.push_back(std::make_pair(3, 0));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 0));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Column center off the left side.
+  center = gfx::Rect(-50, 0, 30, 50);
+
+  // Layout of the tiling data, and expected return order:
+  //     x 0   1   2   3   4
+  //   y ┌───┬───┬───┬───┬───┐
+  // * 0 │  5│ 10│ 15│ 20│ 25│
+  //     ├───┼───┼───┼───┼───┤
+  // * 1 │  4│  9│ 14│ 19│ 24│
+  //     ├───┼───┼───┼───┼───┤
+  // * 2 │  3│  8│ 13│ 18│ 23│
+  //     ├───┼───┼───┼───┼───┤
+  // * 3 │  2│  7│ 12│ 17│ 22│
+  //     ├───┼───┼───┼───┼───┤
+  // * 4 │  1│  6│ 11│ 16│ 21│
+  //     └───┴───┴───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(0, 4));
+  expected.push_back(std::make_pair(0, 3));
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(1, 4));
+  expected.push_back(std::make_pair(1, 3));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(2, 4));
+  expected.push_back(std::make_pair(2, 3));
+  expected.push_back(std::make_pair(2, 2));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(3, 4));
+  expected.push_back(std::make_pair(3, 3));
+  expected.push_back(std::make_pair(3, 2));
+  expected.push_back(std::make_pair(3, 1));
+  expected.push_back(std::make_pair(3, 0));
+  expected.push_back(std::make_pair(4, 4));
+  expected.push_back(std::make_pair(4, 3));
+  expected.push_back(std::make_pair(4, 2));
+  expected.push_back(std::make_pair(4, 1));
+  expected.push_back(std::make_pair(4, 0));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+}
+
+TEST(SpiralIteratorTest, EdgeCases) {
+  TilingData tiling_data(gfx::Size(10, 10), gfx::Size(30, 30), false);
+  std::vector<std::pair<int, int>> expected;
+  gfx::Rect center;
+  gfx::Rect consider;
+  gfx::Rect ignore;
+
+  // Ignore contains, but is not equal to, consider and center.
+  ignore = gfx::Rect(15, 0, 20, 30);
+  consider = gfx::Rect(20, 10, 10, 20);
+  center = gfx::Rect(25, 0, 5, 5);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │   │  I│  *│
+  //    ├───┼───┼───┤
+  //  1 │   │  I│  I│
+  //    ├───┼───┼───┤
+  //  2 │   │  I│  I│
+  //    └───┴───┴───┘
+  expected.clear();
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Center intersects with consider.
+  ignore = gfx::Rect();
+  center = gfx::Rect(0, 15, 30, 15);
+  consider = gfx::Rect(15, 30);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  2│  1│   │
+  //    ├───┼───┼───┤
+  //  1 │  *│  *│  *│
+  //    ├───┼───┼───┤
+  //  2 │  *│  *│  *│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 0));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Consider and ignore are non-intersecting.
+  ignore = gfx::Rect(5, 30);
+  consider = gfx::Rect(25, 0, 5, 30);
+  center = gfx::Rect(15, 0, 1, 1);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  I│  *│  1│
+  //    ├───┼───┼───┤
+  //  1 │  I│   │  2│
+  //    ├───┼───┼───┤
+  //  2 │  I│   │  3│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Center intersects with ignore.
+  consider = gfx::Rect(30, 30);
+  center = gfx::Rect(15, 0, 1, 30);
+  ignore = gfx::Rect(0, 15, 30, 1);
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  3│  *│  2│
+  //    ├───┼───┼───┤
+  //  1 │  I│  *│  I│
+  //    ├───┼───┼───┤
+  //  2 │  4│  *│  1│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(2, 2));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Center and ignore are the same.
+  consider = gfx::Rect(30, 30);
+  center = gfx::Rect(15, 0, 1, 30);
+  ignore = center;
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  4│  *│  3│
+  //    ├───┼───┼───┤
+  //  1 │  5│  *│  2│
+  //    ├───┼───┼───┤
+  //  2 │  6│  *│  1│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(2, 2));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Empty tiling data.
+  TilingData empty_data(gfx::Size(0, 0), gfx::Size(0, 0), false);
+
+  expected.clear();
+
+  TestSpiralIterate(__LINE__, empty_data, consider, ignore, center, expected);
+
+  // Empty consider.
+  ignore = gfx::Rect();
+  center = gfx::Rect(1, 1, 1, 1);
+  consider = gfx::Rect();
+
+  expected.clear();
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Empty center. Note: This arbitrarily puts the center to be off the top-left
+  // corner.
+  consider = gfx::Rect(30, 30);
+  ignore = gfx::Rect();
+  center = gfx::Rect();
+
+  // Layout of the tiling data, and expected return order:
+  //    x 0   1   2
+  //  y ┌───┬───┬───┐
+  //  0 │  1│  2│  6│
+  //    ├───┼───┼───┤
+  //  1 │  3│  4│  5│
+  //    ├───┼───┼───┤
+  //  2 │  7│  8│  9│
+  //    └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 0));
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(2, 2));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Every rect is empty.
+  ignore = gfx::Rect();
+  center = gfx::Rect();
+  consider = gfx::Rect();
+
+  expected.clear();
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+
+  // Center is just to the left of cover, and off of the tiling's left side.
+  consider = gfx::Rect(30, 30);
+  ignore = gfx::Rect();
+  center = gfx::Rect(-20, 0, 19, 30);
+
+  // Layout of the tiling data, and expected return order:
+  //     x 0   1   2
+  //   y ┌───┬───┬───┐
+  // * 0 │  3│  6│  9│
+  //     ├───┼───┼───┤
+  // * 1 │  2│  5│  8│
+  //     ├───┼───┼───┤
+  // * 2 │  1│  4│  7│
+  //     └───┴───┴───┘
+  expected.clear();
+  expected.push_back(std::make_pair(0, 2));
+  expected.push_back(std::make_pair(0, 1));
+  expected.push_back(std::make_pair(0, 0));
+  expected.push_back(std::make_pair(1, 2));
+  expected.push_back(std::make_pair(1, 1));
+  expected.push_back(std::make_pair(1, 0));
+  expected.push_back(std::make_pair(2, 2));
+  expected.push_back(std::make_pair(2, 1));
+  expected.push_back(std::make_pair(2, 0));
+
+  TestSpiralIterate(__LINE__, tiling_data, consider, ignore, center, expected);
+}
+
+}  // namespace
+
+}  // namespace cc