Skip PostRunTestOnMainThread if test is skipped in SetUp()

Test still failed on Win7 with TIMED_OUT. After some checking, I found
PostRunTestOnMainThread should get skipped. There are several RunLoop in
https://cs.chromium.org/chromium/src/chrome/test/base/in_process_browser_test.cc?g=0&l=550
We did not proper setup the browser so shutting down the browser would
potentially have some unknown issues.

TEST: Tested on Win7: https://chromium-swarm.appspot.com/task?id=48bce24f0c843610
Bug: 1025335
Change-Id: I323cf6aaad599fb0661949281dd97e0f58117b63
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1933383Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Sven Zheng <svenzheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719243}

chrome/browser/signin/e2e_tests/live_test.cc

@@ -50,5 +50,12 @@ void LiveTest::TearDown() {
   InProcessBrowserTest::TearDown();
 }
 
+void LiveTest::PostRunTestOnMainThread() {
+  // This test was skipped. Running PostRunTestOnMainThread can cause
+  // TIMED_OUT on Win7.
+  if (skip_test_)
+    return;
+  InProcessBrowserTest::PostRunTestOnMainThread();
+}
 }  // namespace test
 }  // namespace signin

chrome/browser/signin/e2e_tests/live_test.h

@@ -16,6 +16,7 @@ class LiveTest : public InProcessBrowserTest {
   void SetUpInProcessBrowserTestFixture() override;
   void SetUp() override;
   void TearDown() override;
+  void PostRunTestOnMainThread() override;
 
   const TestAccountsUtil* GetTestAccountsUtil() const {
     return &test_accounts_;
@@ -29,4 +30,4 @@ class LiveTest : public InProcessBrowserTest {
 }  // namespace test
 }  // namespace signin
 
-#endif  // CHROME_BROWSER_SIGNIN_E2E_TESTS_LIVE_TEST_H_
\ No newline at end of file
+#endif  // CHROME_BROWSER_SIGNIN_E2E_TESTS_LIVE_TEST_H_