Add notifySyspropsChanged to IBase.

This is used for dynamically updating the atrace
tags in a process, allowing systrace to be invoked
at any time without having to restart a process.

Bug: 31262344
Test: mma
Change-Id: I68ad9566a82d5b1ddf7b00d6af2af6e567526ab0
diff --git a/base/include/hidl/HidlSupport.h b/base/include/hidl/HidlSupport.h
index c604f56..9501190 100644
--- a/base/include/hidl/HidlSupport.h
+++ b/base/include/hidl/HidlSupport.h
@@ -527,6 +527,10 @@
     // HIDL reserved methods follow.
     virtual ::android::hardware::Return<void> interfaceChain(
             std::function<void(const hidl_vec<hidl_string>&)> _hidl_cb) = 0;
+    // This method notifies the interface that one or more system properties have changed.
+    // The default implementation calls report_sysprop_change() in libcutils, which in turn
+    // calls a set of registered callbacks (eg to update trace tags).
+    virtual ::android::hardware::Return<void> notifySyspropsChanged() = 0;
     // descriptor for HIDL reserved methods.
     static const char* descriptor;
 };