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 51c45460b378c2f15239fceba6f3b17969307127..c361fde7268d3cba771f73c79b3ad744ee081424 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -108,6 +108,7 @@
 #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"
@@ -1680,16 +1681,13 @@ void WebViewImpl::didExitFullScreen()
     m_fullscreenController->didExitFullScreen();
 }
 
-void WebViewImpl::animate(double monotonicFrameBeginTime)
+void WebViewImpl::animate(WebFrameTime frameTime)
 {
     TRACE_EVENT0("webkit", "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();
@@ -1706,7 +1704,7 @@ 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());