SkPDF: subset drawImageRect while still deduping

  - Replace SkImageBitmap with SkImageSubset

  - SkBitmapKey becomes trivial for simplicity.

  - SkPDFCanvas::onDraw(Bitmap|Image)Rect now clip and call
    SkCanvas::onDraw(Bitmap|Image)Rect.

  - SkPDFDevice::draw(Bitmap|BitmapRect|Sprite) now convert bitmap
    into SkImageSubset via make_image_subset function.

  - SkPDFDevice::draw(Image|Bitmap)Rect now implemented again.

  - SkPDFDevice::internalDrawImage now performs image subsetting
    as needed, while still deduping properly.

BUG=633528

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2785

Change-Id: I063346d12b0e9c6b6c0c4943ee25400c88aa1a44
Reviewed-on: https://skia-review.googlesource.com/2785
Reviewed-by: Ben Wagner <bungeman@google.com>
5 files changed