Revert 110262 - Have ExtensionHost use TabContents instead of RenderViewHost. Try #2.

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
===================================================================
--- content/browser/renderer_host/render_widget_host_view_mac.mm	(revision 110269)
+++ content/browser/renderer_host/render_widget_host_view_mac.mm	(working copy)
@@ -1670,6 +1670,18 @@
     renderWidgetHostView_->render_widget_host_->WasResized();
 }
 
+- (void)setFrameWithDeferredUpdate:(NSRect)frameRect {
+  [super setFrame:frameRect];
+  [self performSelector:@selector(renderWidgetHostWasResized)
+             withObject:nil
+             afterDelay:0];
+}
+
+- (void)renderWidgetHostWasResized {
+  if (renderWidgetHostView_->render_widget_host_)
+    renderWidgetHostView_->render_widget_host_->WasResized();
+}
+
 - (void)callSetNeedsDisplayInRect {
   DCHECK([NSThread isMainThread]);
   DCHECK(renderWidgetHostView_->call_set_needs_display_in_rect_pending_);