[Reland] Per WebViewScheduler virtual time

third_party/WebKit/public/platform/Platform.h

Index: third_party/WebKit/public/platform/Platform.h
diff --git a/third_party/WebKit/public/platform/Platform.h b/third_party/WebKit/public/platform/Platform.h
index 885a348626efa382279fe6fb63afd55484c1ea4e..3eee9c5aef250152571b2b2f179ca0b89489d592 100644
--- a/third_party/WebKit/public/platform/Platform.h
+++ b/third_party/WebKit/public/platform/Platform.h
@@ -426,6 +426,12 @@ public:
     // it is recommended that the fixed point be no further in the past than the epoch.
     virtual double monotonicallyIncreasingTimeSeconds() { return 0; }
 
+    // Virtual time is used by Headless Chrome for determinism and performance (fast forwarding
+    // of timers). New code should typically use |currentTimeSeconds| and
+    // |monotonicallyIncreasingTimeSeconds| as normal.
+    virtual double virtualTimeSeconds() { return 0; }
+    virtual double monotonicallyIncreasingVirtualTimeSeconds() { return 0; }
+
     // Returns an interface to the main thread. Can be null if blink was initialized on a thread without a message loop.
     BLINK_PLATFORM_EXPORT WebThread* mainThread() const;