Move ThreadWrapper to ProcessThread in base.

Also removes all virtual methods. Permits using a thread from
rtc_base_approved (namely event tracing).

BUG=webrtc:5158
R=tommi@webrtc.org

Review URL: https://codereview.webrtc.org/1469013002

Cr-Commit-Position: refs/heads/master@{#10760}
diff --git a/webrtc/base/platform_thread_unittest.cc b/webrtc/base/platform_thread_unittest.cc
new file mode 100644
index 0000000..ffb60b5
--- /dev/null
+++ b/webrtc/base/platform_thread_unittest.cc
@@ -0,0 +1,53 @@
+/*
+ *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/base/platform_thread.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/scoped_ptr.h"
+#include "webrtc/system_wrappers/include/sleep.h"
+
+namespace webrtc {
+
+// Function that does nothing, and reports success.
+bool NullRunFunction(void* obj) {
+  SleepMs(0);  // Hand over timeslice, prevents busy looping.
+  return true;
+}
+
+TEST(PlatformThreadTest, StartStop) {
+  rtc::scoped_ptr<PlatformThread> thread = PlatformThread::CreateThread(
+      &NullRunFunction, nullptr, "PlatformThreadTest");
+  ASSERT_TRUE(thread->Start());
+  EXPECT_TRUE(thread->Stop());
+}
+
+// Function that sets a boolean.
+bool SetFlagRunFunction(void* obj) {
+  bool* obj_as_bool = static_cast<bool*>(obj);
+  *obj_as_bool = true;
+  SleepMs(0);  // Hand over timeslice, prevents busy looping.
+  return true;
+}
+
+TEST(PlatformThreadTest, RunFunctionIsCalled) {
+  bool flag = false;
+  rtc::scoped_ptr<PlatformThread> thread = PlatformThread::CreateThread(
+      &SetFlagRunFunction, &flag, "RunFunctionIsCalled");
+  ASSERT_TRUE(thread->Start());
+
+  // At this point, the flag may be either true or false.
+  EXPECT_TRUE(thread->Stop());
+
+  // We expect the thread to have run at least once.
+  EXPECT_TRUE(flag);
+}
+
+}  // namespace webrtc