Move Sad Tab implementation out of the TabContentsViews.

content/browser/tab_contents/tab_contents_view.h

Index: content/browser/tab_contents/tab_contents_view.h
diff --git a/content/browser/tab_contents/tab_contents_view.h b/content/browser/tab_contents/tab_contents_view.h
index 05da7c6c8d78df9ff42cf5ea8822f121d3810192..75477b15aa0b2bb14abe73c53635a06432dda4e1 100644
--- a/content/browser/tab_contents/tab_contents_view.h
+++ b/content/browser/tab_contents/tab_contents_view.h
@@ -66,8 +66,7 @@ class CONTENT_EXPORT TabContentsView : public RenderViewHostDelegate::View {
   // trying to find a specific window.
   virtual void SetPageTitle(const string16& title) = 0;
 
-  // Used to notify the view that a tab has crashed so each platform can
-  // prepare the sad tab.
+  // Used to notify the view that a tab has crashed.
   virtual void OnTabCrashed(base::TerminationStatus status,
                             int error_code) = 0;
 
@@ -117,6 +116,17 @@ class CONTENT_EXPORT TabContentsView : public RenderViewHostDelegate::View {
   // TODO(beng): Return a rect rather than using an out param.
   virtual void GetViewBounds(gfx::Rect* out) const = 0;
 
+  // ---------------------------------------------------------------------------
+  // Functions for embedders.
+  // TODO(avi): Figure out where these go on the API surface.
+
+  // Installs a native view to cover the visible web contents. Removed by
+  // |RemoveOverlayView|.
+  virtual void InstallOverlayView(gfx::NativeView view) = 0;
+
+  // Removes the native overlay view installed by |InstallOverlayView|.
+  virtual void RemoveOverlayView() = 0;
+
  protected:
   TabContentsView();  // Abstract interface.