Make ScriptPromiseResolver RefCountedWillBeRefCountedGarbageCollected.

LayoutTests/media/encrypted-media/encrypted-media-lifetime-multiple-mediakeys.html

Index: LayoutTests/media/encrypted-media/encrypted-media-lifetime-multiple-mediakeys.html
diff --git a/LayoutTests/media/encrypted-media/encrypted-media-lifetime-multiple-mediakeys.html b/LayoutTests/media/encrypted-media/encrypted-media-lifetime-multiple-mediakeys.html
index c8aa2073c565ee54f44e200e63c7eaf2f35bd363..c61ccb4108b37a928dad6cf9e15bfb813032c8c1 100644
--- a/LayoutTests/media/encrypted-media/encrypted-media-lifetime-multiple-mediakeys.html
+++ b/LayoutTests/media/encrypted-media/encrypted-media-lifetime-multiple-mediakeys.html
@@ -59,23 +59,27 @@
                 // a reference to the last one created.
                 createMediaKeyWithMediaKeySession().then(function(mediaKeySession) {
                     // Should be 1 MediaKeySession.
-                    assert_equals(numActiveDOMObjectsCreated(), 1);
+                    // Since ScriptPromiseResolver is an ActiveDOMObject,
+                    // MediaKeysInitializer, MediaKeySystemAccessInitializer, and
+                    // ScriptPromiseResolver owned by ContentDecryptionModuleResultPromise are
+                    // also counted. So numActiveDOMObjectsCreated() is 4 when enabling oilpan.
+                    assert_less_than_equal(numActiveDOMObjectsCreated(), 4);
                     return createMediaKeyWithMediaKeySession();
                 }).then(function(mediaKeySession) {
                     // Should be 2 MediaKeySessions.
-                    assert_equals(numActiveDOMObjectsCreated(), 2);
+                    assert_less_than_equal(numActiveDOMObjectsCreated(), 8);
                     return createMediaKeyWithMediaKeySession();
                 }).then(function(mediaKeySession) {
                     // Should be 3 MediaKeySessions.
-                    assert_equals(numActiveDOMObjectsCreated(), 3);
+                    assert_less_than_equal(numActiveDOMObjectsCreated(), 12);
                     return createMediaKeyWithMediaKeySession();
                 }).then(function(mediaKeySession) {
                     // Should be 4 MediaKeySessions.
-                    assert_equals(numActiveDOMObjectsCreated(), 4);
+                    assert_less_than_equal(numActiveDOMObjectsCreated(), 16);
                     return createMediaKeyWithMediaKeySession();
                 }).then(function(mediaKeySession) {
                     // Should be 5 MediaKeySessions.
-                    assert_equals(numActiveDOMObjectsCreated(), 5);
+                    assert_less_than_equal(numActiveDOMObjectsCreated(), 20);
 
                     // |mediaKeys| refers to the most recently created MediaKeys
                     // object.
@@ -90,8 +94,9 @@
                 }).then(function(result) {
                     // In non-Oilpan, numActiveDOMObjectsCreated() is 5
                     // (5 MediaKeySession objects).
-                    // In Oilpan, numActiveDOMObjectsCreated() is 6
-                    // (5 MediaKeySession objects + 1 DOMTimer created in the
+                    // In Oilpan, numActiveDOMObjectsCreated() is 21
+                    // (5 MediaKeySession objects + 15 ScriptPromiseResolvers
+                    // + 1 DOMTimer created in the
                     // above delayToAllowEventProcessingPromise()).
                     assert_true(numActiveDOMObjectsCreated() >= 5);