Changing animate to beginFrame and use struct rather than naked double to allow extension.

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index a79c698484072414f1953b3cd1c6778c9d08d245..10cb1009dbb218b14bccbc01d26b816973154f03 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -109,6 +109,7 @@
 #include "public/platform/Platform.h"
 #include "public/platform/WebDragData.h"
 #include "public/platform/WebFloatPoint.h"
+#include "public/platform/WebFrameTime.h"
 #include "public/platform/WebGestureCurve.h"
 #include "public/platform/WebImage.h"
 #include "public/platform/WebLayerTreeView.h"
@@ -1686,16 +1687,13 @@ void WebViewImpl::didExitFullScreen()
     m_fullscreenController->didExitFullScreen();
 }
 
-void WebViewImpl::animate(double monotonicFrameBeginTime)
+void WebViewImpl::animate(WebFrameTime frameTime)
 {
     TRACE_EVENT0("blink", "WebViewImpl::animate");
 
-    if (!monotonicFrameBeginTime)
-        monotonicFrameBeginTime = monotonicallyIncreasingTime();
-
     // Create synthetic wheel events as necessary for fling.
     if (m_gestureAnimation) {
-        if (m_gestureAnimation->animate(monotonicFrameBeginTime))
+        if (m_gestureAnimation->animate(frameTime))
             scheduleAnimation();
         else {
             endActiveFlingAnimation();
@@ -1712,7 +1710,7 @@ void WebViewImpl::animate(double monotonicFrameBeginTime)
     if (!m_page)
         return;
 
-    PageWidgetDelegate::animate(m_page.get(), monotonicFrameBeginTime);
+    PageWidgetDelegate::animate(m_page.get(), frameTime);
 
     if (m_continuousPaintingEnabled) {
         ContinuousPainter::setNeedsDisplayRecursive(m_rootGraphicsLayer, m_pageOverlays.get());