Fix overflow in number of bytes to erase.

The width and the height were multiplied as int * int.
Now it is int64_t * int64_t.

BUG=chromium:812519

Change-Id: If60bbdd8ee92748559b2e4f3ab57e4463a8006e8
Reviewed-on: https://skia-review.googlesource.com/109781
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed