Address Siva's comments from https://codereview.chromium.org/1877973002/

runtime/vm/compiler.h

 // 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.
 
 #ifndef VM_COMPILER_H_
 #define VM_COMPILER_H_
 
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
 #include "vm/runtime_entry.h"
@@ skipping 143 matching lines @@
 // Class to run optimizing compilation in a background thread.
 // Current implementation: one task per isolate, it dies with the owning
 // isolate.
 // No OSR compilation in the background compiler.
 class BackgroundCompiler : public ThreadPool::Task {
  public:
   virtual ~BackgroundCompiler();
 
   static void EnsureInit(Thread* thread);
 
-  static void Stop(BackgroundCompiler* task);
+  // Stops background compiler of the given isolate.
+  static void Stop(Isolate* isolate);
 
   // Call to optimize a function in the background, enters the function in the
   // compilation queue.
   void CompileOptimized(const Function& function);
 
   void VisitPointers(ObjectPointerVisitor* visitor);
 
   BackgroundCompilationQueue* function_queue() const { return function_queue_; }
   bool is_running() const { return running_; }
 
  private:
   explicit BackgroundCompiler(Isolate* isolate);
 
   virtual void Run();
 
   Isolate* isolate_;
   bool running_;       // While true, will try to read queue and compile.
   bool* done_;         // True if the thread is done.
   Monitor* queue_monitor_;  // Controls access to the queue.
   Monitor* done_monitor_;   // Notify/wait that the thread is done.
 
   BackgroundCompilationQueue* function_queue_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BackgroundCompiler);
 };
 
 }  // namespace dart
 
 #endif  // VM_COMPILER_H_