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..5eed1e402f6dadeea4c71c74bdcd31678ff9026b 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 resendSource, 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_resendSource = resendSource;
         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 +121,14 @@ public:
         return m_data.m_scroll.m_inertial;
     }
 
+    int resendSource() const
+    {

[tdresser, 2015/09/11 15:25:20]

Can we keep this consistent with the other accessors, which assert that the type
is correct?

[wjmaclean, 2015/09/11 15:31:01]

Sure, I'll add an ASSERT in the next version of the patch.

+        if (isScrollEvent())
+            return m_data.m_scroll.m_resendSource;
+
+        return 0;
+    }
+
     bool preventPropagation() const
     {
         ASSERT(m_type == PlatformEvent::GestureScrollUpdate);
@@ -185,6 +194,7 @@ protected:
             float m_velocityY;
             int m_preventPropagation;
             bool m_inertial;
+            int m_resendSource;

[tdresser, 2015/09/11 15:25:20]

Why is this an int?

[wjmaclean, 2015/09/11 15:31:01]

Since there can be multiple BrowserPlugins in a page, the guest will put the
BrowserPlugin's unique ID into the resendSource field, just to check that it
makes it's way back to the right place in the embedder.

[tdresser, 2015/09/11 15:34:10]

Makes sense. Can we clarify the meaning with a better member name (or at least a
comment?).

Maybe something like resendingPluginId?

         } m_scroll;
 
         struct {