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

third_party/WebKit/Source/platform/WebFrameScheduler.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef WebFrameScheduler_h
 #define WebFrameScheduler_h
 
 #include "platform/wtf/RefPtr.h"
 
 #include <memory>
@@ skipping 48 matching lines @@
   virtual RefPtr<WebTaskRunner> SuspendableTaskRunner() = 0;
 
   // Returns the WebTaskRunner for tasks which should never get throttled.
   // This is generally used for executing internal browser tasks which should
   // never be throttled. Ideally only tasks whose performance characteristics
   // are known should be posted to this task runner; for example user
   // JavaScript is discouraged. WebFrameScheduler owns the returned
   // 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; }
 
   // Tells the scheduler a resource load has started. The scheduler may make
   // policy decisions based on this.
   virtual void DidStartLoading(unsigned long identifier) {}
 
   // Tells the scheduler a resource load has stopped. The scheduler may make
   // policy decisions based on this.
   virtual void DidStopLoading(unsigned long identifier) {}
@@ skipping 11 matching lines @@
   // connection (websocket, webrtc, etc). When connection is closed this handle
   // must be destroyed.
   virtual std::unique_ptr<ActiveConnectionHandle> OnActiveConnectionCreated() {
     return nullptr;
   };
 };
 
 }  // namespace blink
 
 #endif  // WebFrameScheduler_h