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 cd21dd728743177506edcafb965d592763bb7db3..946891ece897d39c0d2bd8f0d6040c4906edf6b1 100644
--- a/third_party/WebKit/Source/platform/BUILD.gn
+++ b/third_party/WebKit/Source/platform/BUILD.gn
@@ -2162,6 +2162,11 @@ 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/PushPullFIFOMultithreadTest.cpp",
   ]
 
   configs += [