Mark some flaky tests as disabled on Linux.

chrome/browser/media/encrypted_media_browsertest.cc

Index: chrome/browser/media/encrypted_media_browsertest.cc
diff --git a/chrome/browser/media/encrypted_media_browsertest.cc b/chrome/browser/media/encrypted_media_browsertest.cc
index 5662efe4177c7a8e0253dff2c377be284104b94d..4b0cfdd98dc662ee8fbbf8a1b94ea6a9ef93cf5f 100644
--- a/chrome/browser/media/encrypted_media_browsertest.cc
+++ b/chrome/browser/media/encrypted_media_browsertest.cc
@@ -557,7 +557,7 @@ IN_PROC_BROWSER_TEST_P(EncryptedMediaTest, Playback_VideoClearAudio_WebM) {
 #else
 #define MAYBE_Playback_VP9Video_WebM Playback_VP9Video_WebM
 #endif
-IN_PROC_BROWSER_TEST_P(EncryptedMediaTest, Playback_VP9Video_WebM) {
+IN_PROC_BROWSER_TEST_P(EncryptedMediaTest, MAYBE_Playback_VP9Video_WebM) {
   TestSimplePlayback("bear-320x240-v-vp9_enc-v.webm", kWebMVP9VideoOnly);
 }
 
@@ -567,7 +567,7 @@ IN_PROC_BROWSER_TEST_P(EncryptedMediaTest, Playback_VP9Video_WebM) {
 #else
 #define MAYBE_Playback_AudioOnly_WebM_Opus Playback_AudioOnly_WebM_Opus
 #endif
-IN_PROC_BROWSER_TEST_P(EncryptedMediaTest, Playback_AudioOnly_WebM_Opus) {
+IN_PROC_BROWSER_TEST_P(EncryptedMediaTest, MAYBE_Playback_AudioOnly_WebM_Opus) {
   TestSimplePlayback("bear-320x240-opus-a_enc-a.webm", kWebMAudioOnly);
 }