Add isStable in Parcelable interface

Bug: 156242606
Test: m
Change-Id: I0edc64c8c7f8c9c08384f9d48832549eb026b9d0

libs/binder/include/binder/Parcelable.h

@@ -52,6 +52,12 @@ public:
     //
     // Returns android::OK on success and an appropriate error otherwise.
     virtual status_t readFromParcel(const Parcel* parcel) = 0;
+
+    // 'Stable' means this parcelable is guaranteed to be stable for multiple years.
+    // It must be guaranteed by setting stability field in aidl_interface.
+    // WARNING: isStable() is only expected to be overridden by auto-generated code.
+    // Returns true if this parcelable is stable.
+    virtual bool isStable() const { return false; }
 };  // class Parcelable
 
 #if defined(__clang__)