Fix to asiva's code review comments on TBR Cl.

runtime/vm/debugger_api_impl.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_debugger_api.h"
 
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_state.h"
@@ skipping 778 matching lines @@
   DARTSCOPE(isolate);
   const Library& lib = Library::Handle(Library::GetLibrary(library_id));
   if (lib.IsNull()) {
     return Api::NewError("%s: %" Pd " is not a valid library id",
                          CURRENT_FUNC, library_id);
   }
   return Api::NewHandle(isolate, lib.raw());
 }
 
 
+DART_EXPORT Dart_Handle Dart_LibraryId(Dart_Handle library,
+                                       intptr_t* library_id) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  const Library& lib = Api::UnwrapLibraryHandle(isolate, library);
+  if (lib.IsNull()) {
+    RETURN_TYPE_ERROR(isolate, library, Library);
+  }
+  if (library_id == NULL) {
+    RETURN_NULL_ERROR(library_id);
+  }
+  *library_id = lib.index();
+  return Api::Success();
+}
+
+
 DART_EXPORT Dart_Handle Dart_GetLibraryImports(intptr_t library_id) {
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate != NULL);
   DARTSCOPE(isolate);
   const Library& lib = Library::Handle(Library::GetLibrary(library_id));
   if (lib.IsNull()) {
     return Api::NewError("%s: %" Pd " is not a valid library id",
                          CURRENT_FUNC, library_id);
   }
   const GrowableObjectArray& import_list =
@@ skipping 77 matching lines @@
 
 
 DART_EXPORT char* Dart_GetVmStatus(const char* request) {
   if (strncmp(request, "/isolate/", 9) == 0) {
     return Isolate::GetStatus(request);
   }
   return NULL;
 }
 
 }  // namespace dart