Remove page IDs from three WebContentsObserver APIs that don't need it.

content/browser/renderer_host/render_view_host_delegate.h

Index: content/browser/renderer_host/render_view_host_delegate.h
diff --git a/content/browser/renderer_host/render_view_host_delegate.h b/content/browser/renderer_host/render_view_host_delegate.h
index aa7a0eb39fc51e35cd9680ef45ad9bef749d0dde..c9d3f2d97e514e6ce921eb3081de106fdb9792f9 100644
--- a/content/browser/renderer_host/render_view_host_delegate.h
+++ b/content/browser/renderer_host/render_view_host_delegate.h
@@ -146,8 +146,7 @@ class CONTENT_EXPORT RenderViewHostDelegate {
 
   // The onload handler in the RenderView's main frame has completed.
   virtual void DocumentOnLoadCompletedInMainFrame(
-      RenderViewHost* render_view_host,
-      int32 page_id) {}
+      RenderViewHost* render_view_host) {}
 
   // The page wants to close the active view in this tab.
   virtual void RouteCloseEvent(RenderViewHost* rvh) {}