Introduce WebTaskRunner Patch 1/5

public/platform/WebThread.h

Index: public/platform/WebThread.h
diff --git a/public/platform/WebThread.h b/public/platform/WebThread.h
index 9c7612534d28161ac781432d4390d15925ffae0f..51f204b49c7f448e75445e5258fa6470e871be3f 100644
--- a/public/platform/WebThread.h
+++ b/public/platform/WebThread.h
@@ -34,6 +34,7 @@
 
 namespace blink {
 class WebScheduler;
+class WebTaskRunner;
 class WebTraceLocation;
 
 // Always an integer value.
@@ -69,9 +70,13 @@ public:
     // postTask() and postDelayedTask() take ownership of the passed Task
     // object. It is safe to invoke postTask() and postDelayedTask() from any
     // thread.
+    // TODO(alexclarke): Remove postTask & postDelayedTask.
     virtual void postTask(const WebTraceLocation&, Task*) = 0;
     virtual void postDelayedTask(const WebTraceLocation&, Task*, long long delayMs) = 0;
 
+    // Returns a WebTaskRunner bound to the underlying scheduler's default task queue.
+    virtual WebTaskRunner* taskRunner() { return nullptr; }
+
     virtual bool isCurrentThread() const = 0;
     virtual PlatformThreadId threadId() const { return 0; }