Modify gesture event types for WebView-tag scroll bubbling.

Source/platform/PlatformGestureEvent.h

Index: Source/platform/PlatformGestureEvent.h
diff --git a/Source/platform/PlatformGestureEvent.h b/Source/platform/PlatformGestureEvent.h
index a1d8be5e0506953525615d3b62812b9567fb318b..e50d7db5da223c00118875e9986c2a117c5dcea3 100644
--- a/Source/platform/PlatformGestureEvent.h
+++ b/Source/platform/PlatformGestureEvent.h
@@ -55,7 +55,7 @@ public:
     }
 
     void setScrollGestureData(float deltaX, float deltaY, float velocityX, float velocityY,
-        bool inertial, bool preventPropagation)
+        bool inertial, int resendingPluginId, bool preventPropagation)
     {
         ASSERT(type() == PlatformEvent::GestureScrollBegin
             || type() == PlatformEvent::GestureScrollUpdate
@@ -76,6 +76,7 @@ public:
         m_data.m_scroll.m_velocityX = velocityX;
         m_data.m_scroll.m_velocityY = velocityY;
         m_data.m_scroll.m_inertial = inertial;
+        m_data.m_scroll.m_resendingPluginId = resendingPluginId;
         m_data.m_scroll.m_preventPropagation = preventPropagation;
     }
 
@@ -104,13 +105,13 @@ public:
 
     float velocityX() const
     {
-        ASSERT(m_type == PlatformEvent::GestureScrollUpdate);
+        ASSERT(m_type == PlatformEvent::GestureScrollUpdate || m_type == PlatformEvent::GestureFlingStart);
         return m_data.m_scroll.m_velocityX;
     }
 
     float velocityY() const
     {
-        ASSERT(m_type == PlatformEvent::GestureScrollUpdate);
+        ASSERT(m_type == PlatformEvent::GestureScrollUpdate || m_type == PlatformEvent::GestureFlingStart);
         return m_data.m_scroll.m_velocityY;
     }
 
@@ -120,6 +121,15 @@ public:
         return m_data.m_scroll.m_inertial;
     }
 
+    int resendingPluginId() const
+    {
+        ASSERT(m_type == PlatformEvent::GestureScrollUpdate);

[tdresser, 2015/09/15 13:13:08]

In WebInputEventConversion, we populate the plugin id for GestureScrollBegin and
GestureScrollEnd as well. Why are we inconsistent?

[wjmaclean, 2015/09/15 15:02:48]

Done.

We actually mark the bracketing begin/end that we send in the other CL as
resends, so you're right to think we should add that here.

+        if (isScrollEvent())
+            return m_data.m_scroll.m_resendingPluginId;
+
+        return 0;

[tdresser, 2015/09/15 13:13:08]

Let's return -1 here.

[wjmaclean, 2015/09/15 15:02:48]

Done.

+    }
+
     bool preventPropagation() const
     {
         ASSERT(m_type == PlatformEvent::GestureScrollUpdate);
@@ -185,6 +195,7 @@ protected:
             float m_velocityY;
             int m_preventPropagation;
             bool m_inertial;
+            int m_resendingPluginId;
         } m_scroll;
 
         struct {