TabManager checks if ServiceWorker exists on the suspending process

chrome/browser/memory/tab_manager.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/memory/tab_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <set>
@@ skipping 33 matching lines @@
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "components/metrics/system_memory_stats_recorder.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/memory_pressure_controller.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/render_process_host.h"
+#include "content/public/browser/service_worker_context.h"
+#include "content/public/browser/storage_partition.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/page_importance_signals.h"
 
 #if defined(OS_CHROMEOS)
 #include "ash/common/multi_profile_uma.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/wm_shell.h"
 #include "chrome/browser/memory/tab_manager_delegate_chromeos.h"
 #endif
 
@@ skipping 388 matching lines @@
   // A renderer can be suspended if it's not playing media.
   auto tab_stats = GetUnsortedTabStats();
   for (auto& tab : tab_stats) {
     if (tab.child_process_host_id != render_process_id)
       continue;
     WebContents* web_contents = GetWebContentsById(tab.tab_contents_id);
     if (!web_contents)
       return false;
     if (IsMediaTab(web_contents))
       return false;
+
+    content::ServiceWorkerContext* sw_context =
+        content::BrowserContext::GetDefaultStoragePartition(
+            web_contents->GetBrowserContext())->GetServiceWorkerContext();
+    DCHECK(!sw_context);
+    // -- THIS MUST BE CALLED ON THE IO THREAD --
+    if (sw_context->IsServiceWorkerExistsOnProcess(render_process_id))

[shimazu, 2016/12/13 04:16:36]

This is a problem. Do you have any good idea to call this from IO thread?

[nhiroki, 2016/12/13 04:33:59]

Are we on the UI thread here? If so, we could use RenderProcessHost's worker
counts:
https://cs.chromium.org/chromium/src/content/public/browser/render_process_ho...

[nhiroki, 2016/12/13 04:34:56]

(without thread hopping)

[bashi, 2016/12/13 04:40:17]

Thank you for the info. Yes, we may want to use worker_ref_count() in
MemoryCoordinator::CanSuspendRenderer(). Do you have any idea how many renderers
that have worker_ref_count() > 0? If there are many renderers we can't suspend,
MC wouldn't work well...

+      return false;
   }
   return true;
 }
 
 // static
 bool TabManager::CompareTabStats(const TabStats& first,
                                  const TabStats& second) {
   // Being currently selected is most important to protect.
   if (first.is_selected != second.is_selected)
     return first.is_selected;
@@ skipping 556 matching lines @@
   // platform.
   std::string allow_multiple_discards = variations::GetVariationParamValue(
       features::kAutomaticTabDiscarding.name, "AllowMultipleDiscards");
   return (allow_multiple_discards != "true");
 #else
   return false;
 #endif
 }
 
 }  // namespace memory