Remove SetNotAlive method from the thread class.

Also cleaning up methods with the same name in other classes that are derived from the above method.

R=perkj@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/41759004

Cr-Commit-Position: refs/heads/master@{#8242}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8242 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/system_wrappers/source/condition_variable_unittest.cc

@@ -157,7 +157,6 @@ class CondVarTest : public ::testing::Test {
     // Thus, we need to pin it down inside its Run function (between Grab
     // and Pass).
     ASSERT_TRUE(baton_.Pass(kShortWaitMs));
-    thread_->SetNotAlive();
     ASSERT_TRUE(baton_.Grab(kShortWaitMs));
     ASSERT_TRUE(thread_->Stop());
     delete thread_;