libbinder: BpBinder: hide layout

Currently the layout of mHandle in BpBinder is exposed. This restricts
possible changes that can be made in the future, so removing it while we
can.

Bug: 136027762
Test: N/A
Change-Id: Ie7bb8998c604eccbbd357ea2e276b2fd5ae54523
diff --git a/libs/binder/BpBinder.cpp b/libs/binder/BpBinder.cpp
index f35803c..5ceb218 100644
--- a/libs/binder/BpBinder.cpp
+++ b/libs/binder/BpBinder.cpp
@@ -148,6 +148,10 @@
     IPCThreadState::self()->incWeakHandle(handle, this);
 }
 
+int32_t BpBinder::handle() const {
+    return mHandle;
+}
+
 bool BpBinder::isDescriptorCached() const {
     Mutex::Autolock _l(mLock);
     return mDescriptorCache.size() ? true : false;
diff --git a/libs/binder/include/binder/BpBinder.h b/libs/binder/include/binder/BpBinder.h
index 78f2e1d..b3a1d0b 100644
--- a/libs/binder/include/binder/BpBinder.h
+++ b/libs/binder/include/binder/BpBinder.h
@@ -34,7 +34,7 @@
 public:
     static BpBinder*    create(int32_t handle);
 
-    inline  int32_t     handle() const { return mHandle; }
+    int32_t             handle() const;
 
     virtual const String16&    getInterfaceDescriptor() const;
     virtual bool        isBinderAlive() const;