cc: Implement IndexRect for encapsulating tile indices.

cc/base/index_rect.cc

Index: cc/base/index_rect.cc
diff --git a/cc/base/index_rect.cc b/cc/base/index_rect.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5a9d00370003645f5412edec46a4b399020125eb
--- /dev/null
+++ b/cc/base/index_rect.cc
@@ -0,0 +1,27 @@
+// 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 "cc/base/index_rect.h"
+
+#include "base/strings/stringprintf.h"
+
+namespace cc {
+
+void IndexRect::ClampTo(const IndexRect& other) {
+  left_ = std::max(left_, other.left());
+  top_ = std::max(top_, other.top());
+  right_ = std::min(right_, other.right());
+  bottom_ = std::min(bottom_, other.bottom());
+}
+
+bool IndexRect::Contains(int index_x, int index_y) const {
+  return index_x >= left_ && index_x <= right_ && index_y >= top_ &&
+         index_y <= bottom_;
+}
+
+std::string IndexRect::ToString() const {
+  return base::StringPrintf("%d,%d,%d,%d", left(), right(), top(), bottom());
+}
+
+}  // namespace cc