Move blink scheduler implementation into a component

content/child/webthread_base.h

Index: content/child/webthread_base.h
diff --git a/content/child/webthread_base.h b/content/child/webthread_base.h
index 5d6ebb9b0f05ff1855116f80870e2d8fda1ad696..d8a2dce6e31d0386e2723942699a941c506fefee 100644
--- a/content/child/webthread_base.h
+++ b/content/child/webthread_base.h
@@ -16,8 +16,11 @@ namespace blink {
 class WebTraceLocation;
 }
 
-namespace content {
+namespace scheduler {
 class SingleThreadIdleTaskRunner;
+}
+
+namespace content {
 
 class CONTENT_EXPORT WebThreadBase : public blink::WebThread {
  public:
@@ -48,7 +51,7 @@ class CONTENT_EXPORT WebThreadBase : public blink::WebThread {
 
   // Returns the base::Bind-compatible task runner for posting idle tasks to
   // this thread. Can be called from any thread.
-  virtual SingleThreadIdleTaskRunner* IdleTaskRunner() const = 0;
+  virtual scheduler::SingleThreadIdleTaskRunner* IdleTaskRunner() const = 0;
 
  protected:
   class TaskObserverAdapter;