[Reland] Per WebViewScheduler virtual time

third_party/WebKit/public/platform/WebViewScheduler.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 WebViewScheduler_h
 #define WebViewScheduler_h
 
 #include "WebCommon.h"
 #include "public/platform/WebPassOwnPtr.h"
 
 namespace blink {
 
 class WebFrameScheduler;
 
 class BLINK_PLATFORM_EXPORT WebViewScheduler {
 public:
     virtual ~WebViewScheduler() { }
 
     // The scheduler may throttle tasks associated with background pages.
     virtual void setPageVisible(bool) = 0;
 
     // Creaters a new WebFrameScheduler, the caller is responsible for deleting it.
     virtual WebPassOwnPtr<WebFrameScheduler> createFrameScheduler() = 0;
+
+    // Instructs this WebViewScheduler to use virtual time. When virtual time is enabled
+    // the system doesn't actually sleep for the delays between tasks before executing
+    // them. E.g: A-E are delayed tasks
+    //
+    // |    A   B C  D           E  (normal)
+    // |-----------------------------> time
+    //
+    // |ABCDE                       (virtual time)
+    // |-----------------------------> time
+    virtual void useVirtualTime() = 0;
+
+    // Controls whether or not virtual time is allowed to advance. If virtual time
+    // is not allowed to advance then tasks posted to the WebTaskRunners owned by
+    // any child WebFrameSchedulers will be paused. If virtual time is allowed to
+    // advance then tasks will be run in time order (as usual) but virtual time will
+    // fast forward so that the system doesn't actually sleep for the delays between
+    // tasks before executing them.
+    virtual void setAllowVirtualTimeToAdvance(bool) = 0;

[Sami, 2016/02/01 11:15:07]

Mention that useVirtualTime() must be called before this function.

[alex clarke (OOO till 29th), 2016/02/01 14:16:54]

But it can be used in any order.

 };
 
 } // namespace blink
 
 #endif // WebViewScheduler