Update SkCodec::rewindIfNeeded comment
Update SkCodec::rewindIfNeeded comment

Bug: skia:
Change-Id: I3c08535115b139be80341543daea6d5e23065cd0
Reviewed-on: https://skia-review.googlesource.com/146022
Reviewed-by: Leon Scroggins <995cad867ca30d6399abe011583a53547c8afea1@google.com>
Reviewed-by: Derek Sollenberger <d9b232705cad36bae5cfccf14f9650bb292e6c71@google.com>
Commit-Queue: Derek Sollenberger <d9b232705cad36bae5cfccf14f9650bb292e6c71@google.com>

rubenvb/skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,google/skia,aosp-mirror/platform_external_skia,rubenvb/skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,rubenvb/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,rubenvb/skia,rubenvb/skia,google/skia,google/skia,rubenvb/skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,google/skia,HalCanary/skia-hc,HalCanary/skia-hc,google/skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia