media: Add thumbnail checksum to test-25fps.h264.json.

This CL adds a new thumbnail checksum to test-25fps.h264.json to fix a
failure in guado and rikku after a mesa uprev. buddy is also failing
flakily but it seems to be because it sometimes skips the affected test
(so that's a different bug). Interestingly, other Broadwell devices are
not affected (I don't know why).

See b:149099620 for details on why this is justified. TL;DR: the
difference in the result before and after the mesa uprev is visually
insignificant.

Additionally, we take the chance to fix an incorrect if statement that
was preventing the test from saving the result of the test as a PNG on
failure.

Tast will be modified accordingly after this CL lands.

Bug: b:149099620
Test: video.DecodeAccel.h264 passes on rikku.
Change-Id: I4f1d4a79e11059de4255a14f2e7a6d7c5342c9ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2099408Reviewed-by: Miguel Casas <mcasas@chromium.org>
Reviewed-by: David Staessens <dstaessens@chromium.org>
Commit-Queue: Andres Calderon Jaramillo <andrescj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749759}

media/gpu/test/video_player/frame_renderer_thumbnail.cc

@@ -493,7 +493,7 @@ void FrameRendererThumbnail::ValidateThumbnailTask(bool* success,
   *success = base::Contains(thumbnail_checksums_, md5_string);
 
   // If validation failed, write the thumbnail image to disk.
-  if (!success)
+  if (!(*success))
     SaveThumbnailTask();
 
   done->Signal();

media/test/data/test-25fps.h264.json

@@ -265,6 +265,8 @@
     "# Intel - VA decode to NV12, EGLImage CSC",
     "82a05426b6ef227e5147eb7b710423fb",
     "d1ba5f08cdbcc39ee24d99acaf9477ea",
+    "# Intel - Broadwell - guado and rikku",
+    "e67adcfcb6985b47b0faf29168a56766",
     "# TODO(hiroh): Update X11 value",
     "# Intel - Haswell - X11",
     "# Intel - Ivy Bridge - X11",