Add RoutingIDIssuer to ensure the correctness of ID to be routed.

content/browser/renderer_host/render_widget_helper.cc

Index: content/browser/renderer_host/render_widget_helper.cc
diff --git a/content/browser/renderer_host/render_widget_helper.cc b/content/browser/renderer_host/render_widget_helper.cc
index 1f88835cd275d8fe60cc96cbc4735ac4ed5025ee..b5bb50ff6edfec996497546cb78150dffeb53997 100644
--- a/content/browser/renderer_host/render_widget_helper.cc
+++ b/content/browser/renderer_host/render_widget_helper.cc
@@ -10,12 +10,13 @@
 #include "base/posix/eintr_wrapper.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
+#include "content/browser/dom_storage/session_storage_namespace_impl.h"
 #include "content/browser/gpu/gpu_process_host_ui_shim.h"
 #include "content/browser/gpu/gpu_surface_tracker.h"
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
-#include "content/browser/dom_storage/session_storage_namespace_impl.h"
+#include "content/browser/renderer_host/routing_id_issuer.h"
 #include "content/common/view_messages.h"
 
 namespace content {
@@ -37,6 +38,7 @@ void AddWidgetHelper(int render_process_id,
 
 RenderWidgetHelper::RenderWidgetHelper()
     : render_process_id_(-1),
+      routing_id_issuer_(RoutingIDIssuer::Create()),
       resource_dispatcher_host_(NULL) {
 }
 
@@ -67,7 +69,11 @@ void RenderWidgetHelper::Init(
 }
 
 int RenderWidgetHelper::GetNextRoutingID() {
-  return next_routing_id_.GetNext() + 1;
+  return routing_id_issuer_->IssueNext();
+}
+
+bool RenderWidgetHelper::IsRoutingIDProbablyValid(int routing_id) const {
+  return routing_id_issuer_->IsProbablyValid(routing_id);
 }
 
 // static