Remove FrameViewBase as base class of PluginView.

third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h

Index: third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h b/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
index 2bda3b5c68f68642b59bda16d9d5817a261636f0..6ea10150aacefe04ab0956e71bc4e044433f381b 100644
--- a/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
@@ -34,6 +34,7 @@ namespace blink {
 
 class ExceptionState;
 class Frame;
+class FrameOrPlugin;
 class FrameViewBase;
 class LayoutPart;
 
@@ -105,7 +106,7 @@ class CORE_EXPORT HTMLFrameOwnerElement : public HTMLElement,
                               bool replace_current_item);
   bool IsKeyboardFocusable() const override;
 
-  void DisposeWidgetSoon(FrameViewBase*);
+  void DisposeSoon(FrameOrPlugin*);

[dcheng, 2017/04/17 21:09:04]

Let's fix the naming for this method, since we're changing it in this CL anyway.
I don't have a better suggestion than haraken's suggestion of LayoutController,
so let's just go with that.

[joelhockey, 2017/04/18 00:42:41]

I have renamed the method to DisposeFrameOrPluginSoon.  Haraken's suggestion was
to rename a few different classes.  If we all agree that we want to do that, I
can follow up with that in another CL, and I will also rename this method to the
appropriate new name such as DisposeLayoutControllerSoon.

[dcheng, 2017/04/18 00:56:31]

I think we should implement haraken's suggested names, as it provides a better
hint of what this class hierarchy is used for. Separate CL is fine then I guess.

   void FrameOwnerPropertiesChanged();
 
  private: