Convert SessionService to use new CancelableTaskTracker

chrome/browser/sessions/session_restore.cc

Index: chrome/browser/sessions/session_restore.cc
diff --git a/chrome/browser/sessions/session_restore.cc b/chrome/browser/sessions/session_restore.cc
index 217eb62a6061eea68b8bab21796dc2f4521d4c44..0c939cc13921ec3c62945746e508d657150fd29c 100644
--- a/chrome/browser/sessions/session_restore.cc
+++ b/chrome/browser/sessions/session_restore.cc
@@ -14,6 +14,7 @@
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
 #include "base/metrics/histogram.h"
 #include "base/platform_file.h"
 #include "base/stl_util.h"
@@ -33,6 +34,7 @@
 #include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/webui/ntp/app_launcher_handler.h"
+#include "chrome/common/cancelable_task_tracker.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "content/public/browser/child_process_security_policy.h"
 #include "content/public/browser/dom_storage_context.h"
@@ -523,8 +525,8 @@ class SessionRestoreImpl : public content::NotificationObserver {
         SessionServiceFactory::GetForProfile(profile_);
     DCHECK(session_service);
     session_service->GetLastSession(
-        &request_consumer_,
-        base::Bind(&SessionRestoreImpl::OnGotSession, base::Unretained(this)));
+        base::Bind(&SessionRestoreImpl::OnGotSession, base::Unretained(this)),
+        &cancelable_task_tracker_);
 
     if (synchronous_) {
       {
@@ -711,8 +713,7 @@ class SessionRestoreImpl : public content::NotificationObserver {
     return browser;
   }
 
-  void OnGotSession(SessionService::Handle handle,
-                    std::vector<SessionWindow*>* windows,
+  void OnGotSession(ScopedVector<SessionWindow> windows,

[marja, 2012/12/06 08:21:58]

Is it possible to avoid copying the ScopedVector when passing the param?

[kaiwang, 2012/12/06 18:07:52]

no.. ScopedVector is a non-copyable type like scoped_ptr. So the only way to put
it in Callback is declare like this. I think this is a good thing, the callback
writer knows clearly all the SessionWindows are owned here.

The only member of ScopedVector is an std::vector, and Pass() uses
vector::swap(). So the construction is very cheap.

[kaiwang, 2012/12/06 18:29:31]

Oh, I think I was wrong. It's possible to Bind a 
"const ScopedVector<...>&"
Although I don't feel this makes much sense...

But the case of this CL, SessionCallbacks can own SessionWindows (see old
comment in session_service.h), so the ScopedVector must be modifiable.

[marja, 2012/12/10 18:22:56]

Hmm, so this copy probably gets ScopedVector(RValue other)
called, and it does the swap, so the original ScopedVector is emptied, and
nothing disastrous happens. Ok.

                     SessionID::id_type active_window_id) {
     base::TimeDelta time_to_got_sessions =
         base::TimeTicks::Now() - restore_started_;
@@ -728,13 +729,13 @@ class SessionRestoreImpl : public content::NotificationObserver {
 #endif
     if (synchronous_) {
       // See comment above windows_ as to why we don't process immediately.
-      windows_.swap(*windows);
+      windows_.swap(windows.get());
       active_window_id_ = active_window_id;
       MessageLoop::current()->QuitNow();
       return;
     }
 
-    ProcessSessionWindows(windows, active_window_id);
+    ProcessSessionWindows(&windows.get(), active_window_id);
   }
 
   Browser* ProcessSessionWindows(std::vector<SessionWindow*>* windows,
@@ -1103,7 +1104,7 @@ class SessionRestoreImpl : public content::NotificationObserver {
   std::vector<GURL> urls_to_open_;
 
   // Used to get the session.
-  CancelableRequestConsumer request_consumer_;
+  CancelableTaskTracker cancelable_task_tracker_;
 
   // Responsible for loading the tabs.
   scoped_refptr<TabLoader> tab_loader_;