compositor-worker: Keep worker backing thread alive for the lifetime of the compositor thread.

third_party/WebKit/Source/modules/compositorworker/CompositorWorkerThreadTest.cpp

Index: third_party/WebKit/Source/modules/compositorworker/CompositorWorkerThreadTest.cpp
diff --git a/third_party/WebKit/Source/modules/compositorworker/CompositorWorkerThreadTest.cpp b/third_party/WebKit/Source/modules/compositorworker/CompositorWorkerThreadTest.cpp
index dd55032545cc9bbd9d40510acd53574475899928..26cfa226772c23ba1077fee9ac7281419fb02f8e 100644
--- a/third_party/WebKit/Source/modules/compositorworker/CompositorWorkerThreadTest.cpp
+++ b/third_party/WebKit/Source/modules/compositorworker/CompositorWorkerThreadTest.cpp
@@ -91,7 +91,7 @@ public:
     void TearDown() override
     {
         m_page.clear();
-        CompositorWorkerThread::resetSharedBackingThreadForTest();
+        CompositorWorkerThread::clearSharedBackingThread();
     }
 
     PassOwnPtr<CompositorWorkerThread> createCompositorWorker()
@@ -183,17 +183,17 @@ TEST_F(CompositorWorkerThreadTest, TerminateFirstAndCreateSecond)
     WebThreadSupportingGC* firstThread = &compositorWorker->workerBackingThread().backingThread();
     checkWorkerCanExecuteScript(compositorWorker.get());
 
-    ASSERT_EQ(1u, workerBackingThread->workerScriptCount());
+    ASSERT_EQ(2u, workerBackingThread->workerScriptCount());
     compositorWorker->terminateAndWait();
 
-    ASSERT_EQ(0u, workerBackingThread->workerScriptCount());
+    ASSERT_EQ(1u, workerBackingThread->workerScriptCount());
 
     // Create the second worker. The backing thread is same.
     compositorWorker = createCompositorWorker();
     WebThreadSupportingGC* secondThread = &compositorWorker->workerBackingThread().backingThread();
     EXPECT_EQ(firstThread, secondThread);
     checkWorkerCanExecuteScript(compositorWorker.get());
-    ASSERT_EQ(1u, workerBackingThread->workerScriptCount());
+    ASSERT_EQ(2u, workerBackingThread->workerScriptCount());
 
     compositorWorker->terminateAndWait();
 }
@@ -208,7 +208,7 @@ TEST_F(CompositorWorkerThreadTest, CreatingSecondDuringTerminationOfFirst)
 
     // Request termination of the first worker and create the second worker
     // as soon as possible.
-    EXPECT_EQ(1u, firstWorker->workerBackingThread().workerScriptCount());
+    EXPECT_EQ(2u, firstWorker->workerBackingThread().workerScriptCount());
     firstWorker->terminate();
     // We don't wait for its termination.
     // Note: We rely on the assumption that the termination steps don't run