Add experimental code behind a flag for Content Size Policy

content/browser/loader/resource_dispatcher_host_impl.h

Index: content/browser/loader/resource_dispatcher_host_impl.h
diff --git a/content/browser/loader/resource_dispatcher_host_impl.h b/content/browser/loader/resource_dispatcher_host_impl.h
index 339daec4d5d6a909fe8f05f1e134db52e5d8a370..7fabbf5d7707a8f2027d53c7af92ccd493155794 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.h
+++ b/content/browser/loader/resource_dispatcher_host_impl.h
@@ -58,6 +58,7 @@ namespace content {
 class AppCacheService;
 class AsyncRevalidationManager;
 class CertStore;
+class ContentSizeResourceHandlerManager;
 class LoaderDelegate;
 class NavigationURLLoaderImplCore;
 class RenderFrameHostImpl;
@@ -265,6 +266,10 @@ class CONTENT_EXPORT ResourceDispatcherHostImpl
 
   ResourceScheduler* scheduler() { return scheduler_.get(); }
 
+  ContentSizeResourceHandlerManager* content_size_manager() {
+    return content_size_manager_.get();
+  }
+
   // Called by a ResourceHandler when it's ready to start reading data and
   // sending it to the renderer. Returns true if there are enough file
   // descriptors available for the shared memory buffer. If false is returned,
@@ -627,6 +632,8 @@ class CONTENT_EXPORT ResourceDispatcherHostImpl
 
   std::unique_ptr<ResourceScheduler> scheduler_;
 
+  std::unique_ptr<ContentSizeResourceHandlerManager> content_size_manager_;
+
   // Allows tests to use a mock CertStore. If set, the CertStore must
   // outlive this ResourceDispatcherHostImpl.
   CertStore* cert_store_for_testing_;