Oilpan: Enable Oilpan by default in modules/encryptedmedia

LayoutTests/TestExpectations

Index: LayoutTests/TestExpectations
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index a2f0c7441b91f54b1a35a31828d4fb100f32768f..d2c8d4463c5427d6b81d139809627822d6634090 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -927,6 +927,12 @@ crbug.com/308992 svg/as-object/sizing/svg-in-object-placeholder-height-percentag
 crbug.com/368008 virtual/gpu/fast/canvas/canvas-bg.html [ Skip ]
 crbug.com/368531 virtual/gpu/fast/canvas/canvas-path-addpath.html [ Failure Pass ]
 
+# Oilpan's conservative GC makes the test results flaky.
+# If we can rewrite these tests using asyncGC() the flakiness is gone, but we cannot do it
+# because these tests rely on not going back to the event loop during the test.
+crbug.com/378245 media/encrypted-media/encrypted-media-lifetime-mediakeys.html [ Pass Failure ]
+crbug.com/378245 media/encrypted-media/encrypted-media-lifetime-mediakeysession-reference.html [ Pass Failure ]
+
 # Expectations changes due to switiching to In-renderer Shared Worker.
 crbug.com/327256 fast/workers/shared-worker-lifecycle.html [ Failure Pass ]