Add more comments to SkCodec::getRepetitionCount

Bug: skia:
Change-Id: Icc2d7d78106cb587905a8ddb039bc9bf7ae6ad91
Reviewed-on: https://skia-review.googlesource.com/146021
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>

include/codec/SkCodec.h

@@ -636,20 +636,25 @@ class SK_API SkCodec : SkNoncopyable {
      *
      *  As such, future decoding calls may require a rewind.
      *
-     *  For single-frame images, this will return an empty vector.
+     *  For still (non-animated) image codecs, this will return an empty vector.
      */
     std::vector<FrameInfo> getFrameInfo();
 
     static constexpr int kRepetitionCountInfinite = -1;
 
     /**
-     *  Return the number of times to repeat, if this image is animated.
+     *  Return the number of times to repeat, if this image is animated. This number does not
+     *  include the first play through of each frame. For example, a repetition count of 4 means
+     *  that each frame is played 5 times and then the animation stops.
+     *
+     *  It can return kRepetitionCountInfinite, a negative number, meaning that the animation
+     *  should loop forever.
      *
      *  May require reading the stream to find the repetition count.
      *
      *  As such, future decoding calls may require a rewind.
      *
-     *  For single-frame images, this will return 0.
+     *  For still (non-animated) image codecs, this will return 0.
      */
     int getRepetitionCount() {
         return this->onGetRepetitionCount();