scheduler: Move the Blink scheduler into Blink

third_party/WebKit/public/platform/WebTaskRunner.h

Index: third_party/WebKit/public/platform/WebTaskRunner.h
diff --git a/third_party/WebKit/public/platform/WebTaskRunner.h b/third_party/WebKit/public/platform/WebTaskRunner.h
index 24e07e04f6d97d1974d7941775aea29b70bd24fe..1bd4bd8e6fdc28e9547beee6911b158b7c56a044 100644
--- a/third_party/WebKit/public/platform/WebTaskRunner.h
+++ b/third_party/WebKit/public/platform/WebTaskRunner.h
@@ -13,6 +13,10 @@
 #include <memory>
 #endif
 
+namespace base {
+class SingleThreadTaskRunner;
+}
+
 namespace blink {
 
 class WebTraceLocation;
@@ -57,6 +61,9 @@ public:
     // real time domain.
     virtual double monotonicallyIncreasingVirtualTimeSeconds() const = 0;
 
+    // Returns the underlying task runner object.
+    virtual scoped_refptr<base::SingleThreadTaskRunner> taskRunner() = 0;
+
 #ifdef INSIDE_BLINK
     // Helpers for posting bound functions as tasks.