Speculatively re-enable TestVideoQualityH264.

This was reported as flaky. I am unable to reproduce, which could mean
that the issue is fixed, or it could mean that it only flakes on certain
setups (OS, builds, hardware, etc). To aid investigation I am
speculatively re-enabling it; worst case it gets disabled again.

Bug: 754684
Change-Id: I866679464fce4facde927652751046e062ca1c81
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1761602Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688531}

chrome/browser/media/webrtc/webrtc_video_quality_browsertest.cc

@@ -329,15 +329,8 @@ IN_PROC_BROWSER_TEST_P(WebRtcVideoQualityBrowserTest,
 
 #if BUILDFLAG(RTC_USE_H264)
 
-// Flaky on mac: crbug.com/754684
-#if defined(OS_MACOSX)
-#define MAYBE_MANUAL_TestVideoQualityH264 DISABLED_MANUAL_TestVideoQualityH264
-#else
-#define MAYBE_MANUAL_TestVideoQualityH264 MANUAL_TestVideoQualityH264
-#endif
-
 IN_PROC_BROWSER_TEST_P(WebRtcVideoQualityBrowserTest,
-                       MAYBE_MANUAL_TestVideoQualityH264) {
+                       MANUAL_TestVideoQualityH264) {
   base::ScopedAllowBlockingForTesting allow_blocking;
   // Only run test if run-time feature corresponding to |rtc_use_h264| is on.
   if (!base::FeatureList::IsEnabled(content::kWebRtcH264WithOpenH264FFmpeg)) {