Pepper and WebKit API change to support a plugin knowing if a scrollbar is an overlay one.

third_party/WebKit/Source/WebKit/chromium/src/WebScrollbarImpl.h

Index: third_party/WebKit/Source/WebKit/chromium/src/WebScrollbarImpl.h
===================================================================
--- third_party/WebKit/Source/WebKit/chromium/src/WebScrollbarImpl.h	(revision 91997)
+++ third_party/WebKit/Source/WebKit/chromium/src/WebScrollbarImpl.h	(working copy)
@@ -49,6 +49,7 @@
     ~WebScrollbarImpl();
 
     // WebKit::WebScrollbar methods
+    virtual bool isOverlay();
     virtual void setLocation(const WebRect&);
     virtual int value() const;
     virtual void setValue(int position);
@@ -74,6 +75,8 @@
     virtual int visibleWidth() const;
     virtual WebCore::IntSize contentsSize() const;
     virtual WebCore::IntSize overhangAmount() const;
+    virtual void scrollbarStyleChanged();
+    virtual bool isOnActivePage() const;
 
 private:
     bool onMouseDown(const WebInputEvent& event);