Binder: Split OS to Android and Unix part, abstract GetThreadId out

Bug: 302723053
Test: mma in binder folder
Test: aosp/2616196
Change-Id: I73df8fc453df0edf496960853cb0004f1c3a6a43
diff --git a/libs/binder/trusty/OS.cpp b/libs/binder/trusty/OS.cpp
index 8ec9823..43e06e0 100644
--- a/libs/binder/trusty/OS.cpp
+++ b/libs/binder/trusty/OS.cpp
@@ -28,7 +28,7 @@
 
 using android::base::Result;
 
-namespace android {
+namespace android::binder::os {
 
 Result<void> setNonBlocking(android::base::borrowed_fd /*fd*/) {
     // Trusty IPC syscalls are all non-blocking by default.
@@ -73,4 +73,4 @@
     return -1;
 }
 
-} // namespace android
+} // namespace android::binder::os