Extract ProcessManager from ExtensionSystem.

extensions/browser/lazy_background_task_queue.cc

Index: extensions/browser/lazy_background_task_queue.cc
diff --git a/extensions/browser/lazy_background_task_queue.cc b/extensions/browser/lazy_background_task_queue.cc
index 5ac92de54bf2c805573d6e17b03850d7049d8583..754e59264b50b951f51ed430804d109a5e66ec95 100644
--- a/extensions/browser/lazy_background_task_queue.cc
+++ b/extensions/browser/lazy_background_task_queue.cc
@@ -13,7 +13,6 @@
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/extension_host.h"
 #include "extensions/browser/extension_registry.h"
-#include "extensions/browser/extension_system.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "extensions/browser/notification_types.h"
 #include "extensions/browser/process_manager.h"
@@ -47,9 +46,7 @@ bool LazyBackgroundTaskQueue::ShouldEnqueueTask(
   // extension tasks.
   DCHECK(extension);
   if (BackgroundInfo::HasBackgroundPage(extension)) {
-    ProcessManager* pm = ExtensionSystem::Get(
-        browser_context)->process_manager();
-    DCHECK(pm);
+    ProcessManager* pm = ProcessManager::Get(browser_context);
     ExtensionHost* background_host =
         pm->GetBackgroundHostForExtension(extension->id());
     if (!background_host || !background_host->did_stop_loading())
@@ -82,8 +79,7 @@ void LazyBackgroundTaskQueue::AddPendingTask(
     if (extension && BackgroundInfo::HasLazyBackgroundPage(extension)) {
       // If this is the first enqueued task, and we're not waiting for the
       // background page to unload, ensure the background page is loaded.
-      ProcessManager* pm = ExtensionSystem::Get(
-          browser_context)->process_manager();
+      ProcessManager* pm = ProcessManager::Get(browser_context);
       pm->IncrementLazyKeepaliveCount(extension);
       // Creating the background host may fail, e.g. if |profile| is incognito
       // but the extension isn't enabled in incognito mode.
@@ -130,8 +126,8 @@ void LazyBackgroundTaskQueue::ProcessPendingTasks(
   // Balance the keepalive in AddPendingTask. Note we don't do this on a
   // failure to load, because the keepalive count is reset in that case.
   if (host && BackgroundInfo::HasLazyBackgroundPage(extension)) {
-    ExtensionSystem::Get(browser_context)->process_manager()->
-        DecrementLazyKeepaliveCount(extension);
+    ProcessManager::Get(browser_context)
+        ->DecrementLazyKeepaliveCount(extension);
   }
 }