Switch BaseSessionService to use SequencedWorkerPool instead of FILE thread

chrome/browser/sessions/base_session_service.cc

Index: chrome/browser/sessions/base_session_service.cc
diff --git a/chrome/browser/sessions/base_session_service.cc b/chrome/browser/sessions/base_session_service.cc
index e2d7eba1cab7f5423cf08c8510bffa3c3bba1c6f..5f5b1cf4f866484f20ecac9a60cf9d97a0d33190 100644
--- a/chrome/browser/sessions/base_session_service.cc
+++ b/chrome/browser/sessions/base_session_service.cc
@@ -77,7 +77,9 @@ BaseSessionService::BaseSessionService(SessionType type,
     : profile_(profile),
       weak_factory_(this),
       pending_reset_(false),
-      commands_since_reset_(0) {
+      commands_since_reset_(0),
+      sequence_token_(
+          content::BrowserThread::GetBlockingPool()->GetSequenceToken()) {
   if (profile) {
     // We should never be created when incognito.
     DCHECK(!profile->IsOffTheRecord());
@@ -299,17 +301,22 @@ CancelableTaskTracker::TaskId
 bool BaseSessionService::RunTaskOnBackendThread(
     const tracked_objects::Location& from_here,
     const base::Closure& task) {
-  if (profile_ && BrowserThread::IsMessageLoopValid(BrowserThread::FILE)) {
-    return BrowserThread::PostTask(BrowserThread::FILE, from_here, task);
+  if (RunningInProduction()) {
+    return content::BrowserThread::GetBlockingPool()->
+        PostSequencedWorkerTask(sequence_token_,
+                                from_here,
+                                task);
   } else {
-    // Fall back to executing on the main thread if the file thread
-    // has gone away (around shutdown time) or if we're running as
-    // part of a unit test that does not set profile_.
+    // Fall back to executing on the main thread if the sequence
+    // worker pool has been requested to shutdown (around shutdown
+    // time) or if we're running as part of a unit test that does not
+    // set profile_.
     task.Run();
     return true;
   }
 }
 
 bool BaseSessionService::RunningInProduction() const {
-  return profile_ && BrowserThread::IsMessageLoopValid(BrowserThread::FILE);
+  base::SequencedWorkerPool* pool = content::BrowserThread::GetBlockingPool();
+  return profile_ && !pool->IsShutdownInProgress();

[marja, 2013/08/08 20:16:43]

Why checking IsShutdownInProgress here? Will that somehow be true in tests (like
the function name would hint), or.. is the function name not reflecting what it
does? Will there be "pool" in tests? Do we need the separation between tests and
production code any more?

[oshima, 2013/08/08 20:36:53]

This is just replacement of
BrowserThread::IsMessageLoopValid(BrowserThread::FILE) in original code.
This is to run tasks in UI thread during shutdown, otherwise tasks may not
be processed. I believe test case is handled by | profile_ |


I do agree that method name is a bit misleading though.
I'm happy to rename it to something like TaskShouldRunOnMainThread/UIThread or
something you like. Please let me know.

 }