[scheduler] Add unthrottled-by-blockable task queue to fix touch latency regression.

third_party/WebKit/Source/platform/WebFrameScheduler.h

Index: third_party/WebKit/Source/platform/WebFrameScheduler.h
diff --git a/third_party/WebKit/Source/platform/WebFrameScheduler.h b/third_party/WebKit/Source/platform/WebFrameScheduler.h
index f1ea4505332ce61291aa6c0abb5be50199cd01e6..209a5836e042a2a5ebd7c6b2aa7c60efa38ff24f 100644
--- a/third_party/WebKit/Source/platform/WebFrameScheduler.h
+++ b/third_party/WebKit/Source/platform/WebFrameScheduler.h
@@ -66,6 +66,13 @@ class WebFrameScheduler {
   // WebTaskRunner.
   virtual RefPtr<WebTaskRunner> UnthrottledTaskRunner() = 0;
 
+  // Retuns the WebTaskRunner for tasks which should not be suspended or
+  // throttled, but should be blocked during user gesture.
+  // This is a temporary task runner needed for a fix for touch latency
+  // regression. All tasks from it should be moved to suspendable or
+  // unthrottled task runner.
+  virtual RefPtr<WebTaskRunner> GeneralTaskRunner() = 0;
+
   // Returns the parent WebViewScheduler.
   virtual WebViewScheduler* GetWebViewScheduler() { return nullptr; }