Remove unused field to fix clang build.

runtime/vm/thread_test.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 "platform/assert.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
 #include "vm/unit_test.h"
 #include "vm/profiler.h"
 #include "vm/thread_pool.h"
@@ skipping 91 matching lines @@
 
  private:
   const Object* obj_;
   intptr_t count_;
 };
 
 
 class TaskWithZoneAllocation : public ThreadPool::Task {
  public:
   TaskWithZoneAllocation(Isolate* isolate,
-                         const String& foo,
                          Monitor* monitor,
                          bool* done,
                          intptr_t id)
-      : isolate_(isolate), foo_(foo), monitor_(monitor), done_(done), id_(id) {}
+      : isolate_(isolate), monitor_(monitor), done_(done), id_(id) {}
   virtual void Run() {
     Thread::EnterIsolateAsHelper(isolate_);
     {
       Thread* thread = Thread::Current();
       // Create a zone (which is also a stack resource) and exercise it a bit.
       StackZone stack_zone(thread);
       HANDLESCOPE(thread);
       Zone* zone = thread->zone();
       EXPECT_EQ(zone, stack_zone.GetZone());
       ZoneGrowableArray<bool>* a0 = new(zone) ZoneGrowableArray<bool>(zone, 1);
@@ skipping 34 matching lines @@
     Thread::ExitIsolateAsHelper();
     {
       MonitorLocker ml(monitor_);
       *done_ = true;
       ml.Notify();
     }
   }
 
  private:
   Isolate* isolate_;
-  const String& foo_;
   Monitor* monitor_;
   bool* done_;
   intptr_t id_;
 };
 
 
 TEST_CASE(ManyTasksWithZones) {
   const int kTaskCount = 100;
   Monitor sync[kTaskCount];
   bool done[kTaskCount];
   Isolate* isolate = Thread::Current()->isolate();
-  String& foo = String::Handle(String::New("foo"));
   EXPECT(isolate->heap()->GrowthControlState());
   isolate->heap()->DisableGrowthControl();
   for (int i = 0; i < kTaskCount; i++) {
     done[i] = false;
     Dart::thread_pool()->Run(
-        new TaskWithZoneAllocation(isolate, foo, &sync[i], &done[i], i));
+        new TaskWithZoneAllocation(isolate, &sync[i], &done[i], i));
   }
   for (int i = 0; i < kTaskCount; i++) {
     // Check that main mutator thread can still freely use its own zone.
     String& bar = String::Handle(String::New("bar"));
     if (i % 10 == 0) {
       // Mutator thread is free to independently move in/out/between isolates.
       Thread::ExitIsolate();
     }
     MonitorLocker ml(&sync[i]);
     while (!done[i]) {
@@ skipping 36 matching lines @@
   Thread::ExitIsolate();
   Thread::EnterIsolate(orig);
   // Original zone should be preserved.
   EXPECT_EQ(orig_zone, Thread::Current()->zone());
   EXPECT_STREQ("foo", orig_str);
   delete isos[0];
   delete isos[1];
 }
 
 }  // namespace dart