Support tasks injection into a running VM.

src/debug.h

Index: src/debug.h
diff --git a/src/debug.h b/src/debug.h
index 4440d659dc18198e8c07bde4ca754efcbf7ab396..95673ea7da3192864b6e1c1ff14c856e4a73f6af 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -5,6 +5,7 @@
 #ifndef V8_DEBUG_H_
 #define V8_DEBUG_H_
 
+#include <queue>
 #include "src/allocation.h"
 #include "src/arguments.h"
 #include "src/assembler.h"
@@ -336,6 +337,21 @@ class LockingCommandMessageQueue BASE_EMBEDDED {
 };
 
 
+class LockingTaskQueue BASE_EMBEDDED {
+ public:
+  LockingTaskQueue();
+  ~LockingTaskQueue();
+  void Enqueue(v8::Debug::Task* task);
+  v8::Debug::Task* Dequeue();
+  void Clear();
+
+ private:
+  std::queue<v8::Debug::Task*> queue_;
+  mutable base::Mutex mutex_;
+  DISALLOW_COPY_AND_ASSIGN(LockingTaskQueue);
+};
+
+
 // This class contains the debugger support. The main purpose is to handle
 // setting break points in the code.
 //
@@ -363,6 +379,8 @@ class Debug {
                              v8::Debug::ClientData* client_data = NULL);
   // Enqueue a debugger command to the command queue for event listeners.
   void EnqueueDebugCommand(v8::Debug::ClientData* client_data = NULL);
+  void EnqueueEmbedderTask(v8::Debug::Task* task);
+  bool ProcessEmbedderTasks();
   MUST_USE_RESULT MaybeHandle<Object> Call(Handle<JSFunction> fun,
                                            Handle<Object> data);
   Handle<Context> GetDebugContext();
@@ -593,6 +611,7 @@ class Debug {
   base::Semaphore command_received_;  // Signaled for each command received.
   LockingCommandMessageQueue command_queue_;
   LockingCommandMessageQueue event_command_queue_;
+  LockingTaskQueue embedder_task_queue_;
 
   bool is_active_;
   bool is_suppressed_;