Add Function based profile tree

runtime/vm/signal_handler_android.cc

Index: runtime/vm/signal_handler_android.cc
diff --git a/runtime/vm/signal_handler_android.cc b/runtime/vm/signal_handler_android.cc
index ff468b6fa4a0fe1f36e853efcc77a780eef92afa..d8ea14e0ae803ef8d3525fb2f6347d52b488794e 100644
--- a/runtime/vm/signal_handler_android.cc
+++ b/runtime/vm/signal_handler_android.cc
@@ -66,6 +66,20 @@ uintptr_t SignalHandler::GetDartStackPointer(const mcontext_t& mcontext) {
 }
 
 
+uintptr_t SignalHandler::GetLinkRegister(const mcontext_t& mcontext) {
+  uintptr_t lr = 0;
+#if defined(TARGET_ARCH_ARM)
+  lr = static_cast<uintptr_t>(mcontext.arm_lr);
+#elif defined(TARGET_ARCH_ARM64)
+  lr = static_cast<uintptr_t>(mcontext.regs[30]);
+  UNIMPLEMENTED();
+#else
+  UNIMPLEMENTED();
+#endif  // TARGET_ARCH_...
+  return lr;
+}
+
+
 void SignalHandler::Install(SignalAction action) {
   struct sigaction act;
   memset(&act, 0, sizeof(act));