Support to enable profiling dynamically.

* Add an additonal reserved method setHALInstrumentation to
  enable/disable instrumentation during the hal execution.

Test: make hidl-gen
Change-Id: Iaf20e3f798a51b111bffd2e7294973bce0cabf9e
diff --git a/generateCpp.cpp b/generateCpp.cpp
index a4af202..e3ce85c 100644
--- a/generateCpp.cpp
+++ b/generateCpp.cpp
@@ -537,6 +537,14 @@
     out << " {\n";
     out.indent();
 
+    if (method->isHidlReserved()
+        && method->overridesCppImpl(IMPL_PASSTHROUGH)) {
+        method->cppImpl(IMPL_PASSTHROUGH, out);
+        out.unindent();
+        out << "}\n\n";
+        return OK;
+    }
+
     const bool returnsValue = !method->results().empty();
     const TypedVar *elidedReturn = method->canElideCallback();