Force MimeHandlerView to always use BrowserPlugin

content/browser/frame_host/render_widget_host_view_guest.cc

Index: content/browser/frame_host/render_widget_host_view_guest.cc
diff --git a/content/browser/frame_host/render_widget_host_view_guest.cc b/content/browser/frame_host/render_widget_host_view_guest.cc
index 129703549c77496c49a0c91577ff40800aada989..273ec3cb30ba8377f4d58944aaf2b1c4298bc0b1 100644
--- a/content/browser/frame_host/render_widget_host_view_guest.cc
+++ b/content/browser/frame_host/render_widget_host_view_guest.cc
@@ -353,9 +353,13 @@ gfx::NativeView RenderWidgetHostViewGuest::GetNativeView() const {
   if (!guest_)
     return gfx::NativeView();
 
-  RenderWidgetHostView* rwhv = guest_->GetOwnerRenderWidgetHostView();
+  if (guest_->IsMimeHandlerViewGuest())

[lazyboy, 2016/07/22 01:03:30]

I'm not sure I followed why this was needed.

Please add a comment why GetOwnerRWHV doesn't work.

[EhsanK, 2016/07/27 22:34:47]

If we have --use-cross-process-frames-for-guests and create an app
with a <webview> and set the webview.src to a pdf url, then:
1- webview will have a RenderWidgetHostViewChildFrame
2- webview is the embedder
3- PDF will have a RenderWidgetHostViewGuest.

Now GetOwneRenderWidgetHostView()->GetNativeView() crashes because of the
NOTREACHED() in RWHVCF.

After discussion with Lucas we decided to implement GetNativeView() for RWHVCF
instead. So this is reset to master.

+    return guest_->GetTopLevelRenderWidgetHostView()->GetNativeView();
+
+  RenderWidgetHostView* rwhv = GetOwnerRenderWidgetHostView();
   if (!rwhv)
     return gfx::NativeView();
+
   return rwhv->GetNativeView();
 }