cc: Fix BytesPerPixel issue and refactor.

cc/resources/resource_util.cc

Index: cc/resources/resource_util.cc
diff --git a/cc/resources/resource_util.cc b/cc/resources/resource_util.cc
new file mode 100644
index 0000000000000000000000000000000000000000..08c0bf6066878f9e25639311b4c73311d236a289
--- /dev/null
+++ b/cc/resources/resource_util.cc
@@ -0,0 +1,66 @@
+// Copyright 2015 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/resources/resource_util.h"
+
+#include "base/numerics/safe_math.h"
+#include "cc/base/math_util.h"
+
+namespace cc {
+
+// static
+size_t ResourceUtil::CheckedSizeInBytes(const gfx::Size& size,
+                                        ResourceFormat format) {
+  DCHECK(VerifySizeInBytes(size, format));
+  base::CheckedNumeric<size_t> checked_value = BitsPerPixel(format);
+  checked_value *= size.width();
+  checked_value *= size.height();
+  checked_value /= 8;
+  return checked_value.ValueOrDie();
+}
+
+// static
+size_t ResourceUtil::UncheckedWidthInBytes(size_t width,
+                                           ResourceFormat format) {
+  size_t bytes_per_row = width * static_cast<size_t>(BitsPerPixel(format)) / 8;
+  return bytes_per_row;
+}
+
+// static
+size_t ResourceUtil::UncheckedWidthInBytesAligned(size_t width,
+                                                  ResourceFormat format) {
+  // Use 4-byte row alignment (OpenGL default) for upload performance.
+  // Assuming that GL_UNPACK_ALIGNMENT has not changed from default.
+  return MathUtil::RoundUp<size_t>(UncheckedWidthInBytes(width, format), 4u);
+}
+
+// static
+size_t ResourceUtil::UncheckedSizeInBytes(const gfx::Size& size,
+                                          ResourceFormat format) {
+  DCHECK(VerifySizeInBytes(size, format));
+  return size.height() * UncheckedWidthInBytes(size.width(), format);
+}
+
+// static
+size_t ResourceUtil::UncheckedSizeInBytesAligned(const gfx::Size& size,
+                                                 ResourceFormat format) {
+  DCHECK(VerifySizeInBytes(size, format));
+  return size.height() * UncheckedWidthInBytesAligned(size.width(), format);
+}
+
+// static
+bool ResourceUtil::VerifySizeInBytes(const gfx::Size& size,
+                                     ResourceFormat format) {
+  base::CheckedNumeric<size_t> checked_value = BitsPerPixel(format);
+  checked_value *= size.width();
+  checked_value *= size.height();
+  if (!checked_value.IsValid())
+    return false;
+  size_t value = checked_value.ValueOrDie();
+  if ((value % 8) != 0)
+    return false;
+  return true;
+}
+
+}  // namespace cc