missed enabling one color test on linux

In https://chromium-review.googlesource.com/c/chromium/src/+/1151715
I missed one of the tests. Enable it now.

Bug: 767926
Change-Id: I6c8aaa9c6e5a955be747df4fba1f8a3e95166ca7
Reviewed-on: https://chromium-review.googlesource.com/1159348Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Fredrik Hubinette <hubbe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580253}

content/browser/media/media_color_browsertest.cc

@@ -39,13 +39,7 @@ IN_PROC_BROWSER_TEST_F(MediaColorTest, Yuv444pTheora) {
 }
 #endif  // !defined(OS_ANDROID)
 
-// This fails on Linux: http://crbug.com/767926.
-#if defined(OS_LINUX)
-#define MAYBE_Yuv420pVp8 DISABLED_Yuv420pVp8
-#else
-#define MAYBE_Yuv420pVp8 Yuv420pVp8
-#endif
-IN_PROC_BROWSER_TEST_F(MediaColorTest, MAYBE_Yuv420pVp8) {
+IN_PROC_BROWSER_TEST_F(MediaColorTest, Yuv420pVp8) {
   RunColorTest("yuv420p.webm");
 }