media/gpu/test: Fix too large event timeout used in video decoder tests.

This CL fixes a small bug in the video_decode_accelerator_tests that can cause
the video decoder tests to wait longer for an event than the maximum specified
timeout.

TEST=./video_decode_accelerator_tests on eve

BUG=None

Change-Id: I1febbf335afffc00166c3b5e21139367bc68ad91
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1735589Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Commit-Queue: David Staessens <dstaessens@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683915}

media/gpu/test/video_player/video_player.cc

@@ -157,7 +157,7 @@ bool VideoPlayer::WaitForEvent(VideoPlayerEvent event,
       return false;
 
     const base::TimeTicks start_time = base::TimeTicks::Now();
-    event_cv_.TimedWait(max_wait);
+    event_cv_.TimedWait(max_wait - time_waiting);
     time_waiting += base::TimeTicks::Now() - start_time;
   }
 }