PlatformThreadHandle: remove public id() interface

base/threading/thread_unittest.cc

Index: base/threading/thread_unittest.cc
diff --git a/base/threading/thread_unittest.cc b/base/threading/thread_unittest.cc
index 3c3541657ebffbe5c2b0cbd5e37340509764598e..999cc7af30559d636f7c354bc2b2a03df1e0f3d7 100644
--- a/base/threading/thread_unittest.cc
+++ b/base/threading/thread_unittest.cc
@@ -194,6 +194,20 @@ TEST_F(ThreadTest, ThreadName) {
   EXPECT_EQ("ThreadName", a.thread_name());
 }
 
+TEST_F(ThreadTest, ThreadId) {
+  Thread a("ThreadId0");
+  Thread b("ThreadId1");
+  a.StartAndWaitForTesting();
+  b.StartAndWaitForTesting();
+
+  // A started thread should have a valid ID.
+  EXPECT_NE(base::kInvalidThreadId, a.thread_id());
+  EXPECT_NE(base::kInvalidThreadId, b.thread_id());
+
+  // Each thread should have a different thread ID.
+  EXPECT_NE(a.thread_id(), b.thread_id());
+}
+
 // Make sure Init() is called after Start() and before
 // WaitUntilThreadInitialized() returns.
 TEST_F(ThreadTest, SleepInsideInit) {