Changes to support dprof and Observatory profiler UIs

runtime/vm/native_symbol_win.cc

Index: runtime/vm/native_symbol_win.cc
diff --git a/runtime/vm/native_symbol_win.cc b/runtime/vm/native_symbol_win.cc
index b44633f9786a1334dc4a99a1c47581f55e4900a2..add6bf597211bb0cedc45d7f389906a57e936e84 100644
--- a/runtime/vm/native_symbol_win.cc
+++ b/runtime/vm/native_symbol_win.cc
@@ -47,7 +47,7 @@ void NativeSymbolResolver::ShutdownOnce() {
 }
 
 
-char* NativeSymbolResolver::LookupSymbolName(uintptr_t pc) {
+char* NativeSymbolResolver::LookupSymbolName(uintptr_t pc, uintptr_t* start) {
   static const intptr_t kMaxNameLength = 2048;
   static const intptr_t kSymbolInfoSize = sizeof(SYMBOL_INFO);  // NOLINT.
   static char buffer[kSymbolInfoSize + kMaxNameLength];
@@ -56,6 +56,9 @@ char* NativeSymbolResolver::LookupSymbolName(uintptr_t pc) {
   if (!running_) {
     return NULL;
   }
+  if (start != NULL) {
+    *start = NULL;
+  }
 #if 0
   memset(&buffer[0], 0, sizeof(buffer));
   HANDLE hProcess = GetCurrentProcess();