Souped-up SkTextBlob.

Refactored text blob backend for improved performance: instead of using
separate buffers for runs/positions/glyphs, everything is now packed in
a consolidated slab (including the SkTextBlob object itself!).

Benefits:

 * number of allocations per blob construction reduced from ~4 to 1
   (also minimizes internal fragmentation)
 * run record size reduced by 8 bytes

This takes the blob construction overhead down to negligible levels
(for the current Blink uncached textblob implementation).

Unfortunately, the code is much more finicky (run merging in
particular) -- hence the assert spree.

Multi-run blobs are vulnerable to realloc storms but this is not a
problem at the moment because Blink is using one-run blobs 99% of the
time. Will be addressed in the future.

R=mtklein@google.com, reed@google.com, robertphillips@google.com

Committed: https://skia.googlesource.com/skia/+/13645ea0ea87038ebd71be3bd6d53b313069a9e4

Author: fmalita@chromium.org

Review URL: https://codereview.chromium.org/581173003

0 files changed, 0 insertions, 0 deletions