rename new GM

Our new srgb_color_filter (in gm/srgb_color_filter.cpp) is awfully
similar to the existing srgb_colorfilter (in gm/srgb.cpp).

Let's rename the new one.

Change-Id: I8c7816c377cc4342388be51632353882a1bc5241
Reviewed-on: https://skia-review.googlesource.com/26525
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
2 files changed