Remove unused test data under content/common/gpu/testdata/.

content/common/gpu/testdata/red-green.README

-red-green video files in this directory and their provenance:
-
-red-green.h264:
-  Using ffmpeg version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, generated with
-  red-green.mp4 (https://codereview.chromium.org/8342021):
-  ffmpeg -i red-green.mp4 -vcodec copy -vbsf h264_mp4toannexb \
-      -an red-green.h264
-
-red-green.h264.md5:
-  MD5s of RGB thumbnail rendered version of red-green.h264 decoded with Intel
-  VAAPI on Ivy Bridge and Sandy Bridge and V4L2VDA on Exynos.
-  Written out by video_decode_accelerator_unittest.
-  These differ between implementations because color space-converted frames are
-  not specified to the last bit and GLES shader/texture filtering
-  precision varies.
-
-Copyright (c) 2012 The Khronos Group Inc.
-
-Permission is hereby granted, free of charge, to any person obtaining a
-copy of this software and/or associated documentation files (the
-"Materials"), to deal in the Materials without restriction, including
-without limitation the rights to use, copy, modify, merge, publish,
-distribute, sublicense, and/or sell copies of the Materials, and to
-permit persons to whom the Materials are furnished to do so, subject to
-the following conditions:
-
-The above copyright notice and this permission notice shall be included
-in all copies or substantial portions of the Materials.
-
-THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.