Introduce chrome://flags/#network-prediction-options-for-service-worker

content/browser/service_worker/service_worker_context_wrapper.cc

Index: content/browser/service_worker/service_worker_context_wrapper.cc
diff --git a/content/browser/service_worker/service_worker_context_wrapper.cc b/content/browser/service_worker/service_worker_context_wrapper.cc
index a27d006e613c511fde81a788287217ff71b9bad5..ff9f587d0fc887424825f7f4d1e17fe3a42c8bed 100644
--- a/content/browser/service_worker/service_worker_context_wrapper.cc
+++ b/content/browser/service_worker/service_worker_context_wrapper.cc
@@ -20,6 +20,7 @@
 #include "base/single_thread_task_runner.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/browser/service_worker/embedded_worker_status.h"
 #include "content/browser/service_worker/service_worker_context_core.h"
 #include "content/browser/service_worker/service_worker_context_observer.h"
@@ -826,6 +827,93 @@ void ServiceWorkerContextWrapper::DidDeleteAndStartOver(
                          &ServiceWorkerContextObserver::OnStorageWiped);
 }
 
+void ServiceWorkerContextWrapper::StartServiceWorkerForNavigationPreconnect(
+    const GURL& document_url,
+    RenderProcessHost* host,
+    const ResultCallback& callback) {
+  TRACE_EVENT1("ServiceWorker", "StartServiceWorkerForNavigationPreconnect",
+               "document_url", document_url.spec());
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  if (!host || !RenderProcessHostImpl::IsSuitableHost(
+                   host, host->GetBrowserContext(), document_url)) {
+    callback.Run(false);
+    return;
+  }
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&ServiceWorkerContextWrapper::
+                     DidCheckRenderProcessForNavigationPreconnect,
+                 this, document_url, host->GetID(), callback));
+}
+
+void ServiceWorkerContextWrapper::DidCheckRenderProcessForNavigationPreconnect(
+    const GURL& document_url,
+    int render_process_id,
+    const ResultCallback& callback) {
+  TRACE_EVENT1("ServiceWorker", "DidCheckRenderProcessForNavigationPreconnect",
+               "document_url", document_url.spec());
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (!context_core_) {
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                            base::Bind(callback, false));
+    return;
+  }
+  FindReadyRegistrationForDocument(
+      document_url, base::Bind(&ServiceWorkerContextWrapper::
+                                   DidFindRegistrationForNavigationPreconnect,
+                               this, render_process_id, callback));
+}
+
+void ServiceWorkerContextWrapper::DidFindRegistrationForNavigationPreconnect(
+    int render_process_id,
+    const ResultCallback& callback,
+    ServiceWorkerStatusCode status,
+    scoped_refptr<ServiceWorkerRegistration> registration) {
+  TRACE_EVENT0("ServiceWorker", "DidFindRegistrationForNavigationPreconnect");
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (status != SERVICE_WORKER_OK || !registration->active_version()) {
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                            base::Bind(callback, false));
+    return;
+  }
+
+  if (registration->active_version()->fetch_handler_existence() ==
+      ServiceWorkerVersion::FetchHandlerExistence::DOES_NOT_EXIST) {
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                            base::Bind(callback, false));
+    return;
+  }
+
+  // Add the process reference of |render_process_id| not to launch a new
+  // renderer process for the service worker.
+  context_core_->process_manager()->AddProcessReferenceToPattern(
+      registration->pattern(), render_process_id);
+
+  registration->active_version()->StartWorker(
+      ServiceWorkerMetrics::EventType::PRECONNECT,
+      base::Bind(&ServiceWorkerContextWrapper::
+                     DidStartServiceWorkerForNavigationPreconnect,
+                 this, registration->pattern(), render_process_id, callback));
+}
+
+void ServiceWorkerContextWrapper::DidStartServiceWorkerForNavigationPreconnect(
+    const GURL& pattern,
+    int render_process_id,
+    const ResultCallback& callback,
+    ServiceWorkerStatusCode code) {
+  TRACE_EVENT1("ServiceWorker", "DidStartServiceWorkerForNavigationPreconnect",
+               "url", pattern.spec());
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  // Remove the process reference added in
+  // DidFindRegistrationForNavigationPreconnect.
+  context_core_->process_manager()->RemoveProcessReferenceFromPattern(
+      pattern, render_process_id);
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                          base::Bind(callback, code == SERVICE_WORKER_OK));
+}
+
 void ServiceWorkerContextWrapper::BindWorkerFetchContext(
     int render_process_id,
     int service_worker_provider_id,