Fix frame coordinate translation issue with scroll views.

third_party/WebKit/Source/web/WebInputEventConversion.cpp

Index: third_party/WebKit/Source/web/WebInputEventConversion.cpp
diff --git a/third_party/WebKit/Source/web/WebInputEventConversion.cpp b/third_party/WebKit/Source/web/WebInputEventConversion.cpp
index 7b9defc7bf238a88ca6681c5367b07a8f38c8403..b423634cd7b53e865115f971b43b1d0dbe410c72 100644
--- a/third_party/WebKit/Source/web/WebInputEventConversion.cpp
+++ b/third_party/WebKit/Source/web/WebInputEventConversion.cpp
@@ -196,6 +196,13 @@ WebMouseEventBuilder::WebMouseEventBuilder(const FrameView* plugin_parent,
     *static_cast<WebMouseEvent*>(this) =
         event.NativeEvent()->FlattenTransform();
     WebFloatPoint absolute_root_frame_location = PositionInRootFrame();
+
+    // Translate the absolute position to content coordinates.

[mustaq, 2017/04/11 15:20:09]

This particular change is not related to the bug because it is about mouse
events, right?

I have the following concern here, mostly about the original code. So I suggest
deferring the mouse event change, adding just a TODO in this CL.

I couldn't explain the difference of the original code here (the use of
PositionInRootFrame() in particular) with
WebPluginContainerImpl::HandleTouchEvent which doesn't do this. Also, the
transform in HandleTouchEvent should be moved here for sake of better
readability/consistency too.

+    if (plugin_parent) {
+      absolute_root_frame_location =
+          plugin_parent->RootFrameToContents(absolute_root_frame_location);
+    }
+
     IntPoint local_point = RoundedIntPoint(layout_item.AbsoluteToLocal(
         absolute_root_frame_location, kUseTransforms));
     SetPositionInWidget(local_point.X(), local_point.Y());