Bug 215300 – Address additional review feedback from r265360

• Status: ASSIGNED
• Component: Canvas

[Kenneth Russell]

From Bug 183438:

- Refactor copyPremultipliedToPremultiplied and copyUnpremultipliedToUnpremultiplied in Source/WebCore/platform/graphics/ImageBufferBackend.cpp .

- Remove comment which was added in place of the previous assert in copyImagePixelsAccelerated in Source/WebCore/platform/graphics/cg/ImageBufferCGBackend.cpp .

[Said Abou-Hallawa]

Also

- The members: m_originClean, m_premultiplyAlpha and m_forciblyPremultiplyAlpha of ImageBitmap can be replaced by ImageBuffer::SerializationState. This will eliminate the need to sync the members of ImageBitmap and ImageBuffer::SerializationState. Also the whole struct can be copied in many places from std::pair<std::unique_ptr<ImageBuffer>, ImageBuffer::SerializationState> to ImageBitmap and vice versa.

[Said Abou-Hallawa]

Another approach is to make SerializationState enum class type and have an OptionSet< SerializationState> be stored in ImageBitmap:

enum class SerializationState {
    OriginClean = 1 << 0,
    PremultiplyAlpha = 1 << 1,
    ForciblyPremultiplyAlpha = 1 << 2,
};


class ImageBitmap {
public:
    bool originClean() const { return m_serializationState.contains(SerializationState::OriginClean); }

private:
    OptionSet<SerializationState> m_serializationState;
};

[Radar WebKit Bug Importer]

<rdar://problem/67105644>