Add WebThread in AudioDestination to support AudioWorkletThread

third_party/WebKit/Source/platform/BUILD.gn

Index: third_party/WebKit/Source/platform/BUILD.gn
diff --git a/third_party/WebKit/Source/platform/BUILD.gn b/third_party/WebKit/Source/platform/BUILD.gn
index cb0e0ebdc746e807aa36989e8af1b852cfacf229..154099b256f97bdf0a781535c086f1c311e0123f 100644
--- a/third_party/WebKit/Source/platform/BUILD.gn
+++ b/third_party/WebKit/Source/platform/BUILD.gn
@@ -2163,6 +2163,11 @@ source_set("unit_tests") {
 
     # TODO(toyoshim): Remove Platform dependency and move to loader/BUILD.gn
     "loader/fetch/ResourceResponseTest.cpp",
+
+    # TODO(hongchan): Platform::Current()->CreateThread() returns nullptr
+    # without adding the test file into this section. Remove platform dependency
+    # when creating a valid thread becomes possible in the Blink unit test.
+    "audio/PushPullFIFOSmokeTest.cpp",
   ]
 
   configs += [