TabManager checks if ServiceWorker exists on the suspending process

chrome/browser/memory/tab_manager.cc

Index: chrome/browser/memory/tab_manager.cc
diff --git a/chrome/browser/memory/tab_manager.cc b/chrome/browser/memory/tab_manager.cc
index b6062ab348a7fc4de577743cd6eddddf47e7aff5..04c6a4bf10f93f2f874c8c787a639687118ad845 100644
--- a/chrome/browser/memory/tab_manager.cc
+++ b/chrome/browser/memory/tab_manager.cc
@@ -51,6 +51,8 @@
 #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"
 
@@ -459,6 +461,14 @@ bool TabManager::CanSuspendBackgroundedRenderer(int render_process_id) {
       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;
 }