Add IPC::Sender and GetRoutingID() to WebContents for convenience and safety.

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index c6f55f59b1b7b899feca2007186f235a17867578..d68e148c22f9282d91aef074ea2d6400de4c071a 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -14,6 +14,7 @@
 #include "content/public/browser/page_navigator.h"
 #include "content/public/browser/save_page_type.h"
 #include "content/public/browser/web_ui.h"
+#include "ipc/ipc_sender.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/native_widget_types.h"
 #include "webkit/glue/window_open_disposition.h"
@@ -45,7 +46,7 @@ class WebContentsView;
 struct RendererPreferences;
 
 // Describes what goes in the main content area of a tab.
-class WebContents : public PageNavigator {
+class WebContents : public PageNavigator, public IPC::Sender {
  public:
   // |base_web_contents| is used if we want to size the new WebContents's view
   // based on the view of an existing WebContents.  This can be NULL if not
@@ -110,6 +111,10 @@ class WebContents : public PageNavigator {
   // Gets the current RenderViewHost for this tab.
   virtual RenderViewHost* GetRenderViewHost() const = 0;
 
+  // Gets the current RenderViewHost's routing id. Returns
+  // MSG_ROUTING_NONE when there is no RenderViewHost.
+  virtual int GetRoutingID() const = 0;
+
   // Returns the currently active RenderWidgetHostView. This may change over
   // time and can be NULL (during setup and teardown).
   virtual content::RenderWidgetHostView* GetRenderWidgetHostView() const = 0;