Fix predictable mode when job based sweeping is off.

BUG=
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/697423002

Cr-Commit-Position: refs/heads/master@{#25113}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25113 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap/mark-compact.cc

@@ -456,7 +456,6 @@ class MarkCompactCollector::SweeperTask : public v8::Task {
 void MarkCompactCollector::StartSweeperThreads() {
   DCHECK(free_list_old_pointer_space_.get()->IsEmpty());
   DCHECK(free_list_old_data_space_.get()->IsEmpty());
-  sweeping_in_progress_ = true;
   V8::GetCurrentPlatform()->CallOnBackgroundThread(
       new SweeperTask(heap(), heap()->old_data_space()),
       v8::Platform::kShortRunningTask);
@@ -471,13 +470,15 @@ void MarkCompactCollector::EnsureSweepingCompleted() {
 
   // If sweeping is not completed or not running at all, we try to complete it
   // here.
-  if (!IsSweepingCompleted()) {
+  if (FLAG_predictable || !IsSweepingCompleted()) {
     SweepInParallel(heap()->paged_space(OLD_DATA_SPACE), 0);
     SweepInParallel(heap()->paged_space(OLD_POINTER_SPACE), 0);
   }
   // Wait twice for both jobs.
+  if (!FLAG_predictable) {
     pending_sweeper_jobs_semaphore_.Wait();
     pending_sweeper_jobs_semaphore_.Wait();
+  }
   ParallelSweepSpacesComplete();
   sweeping_in_progress_ = false;
   RefillFreeList(heap()->paged_space(OLD_DATA_SPACE));
@@ -4185,7 +4186,7 @@ void MarkCompactCollector::SweepSpaces() {
       SweepSpace(heap()->old_pointer_space(), CONCURRENT_SWEEPING);
       SweepSpace(heap()->old_data_space(), CONCURRENT_SWEEPING);
     }
-
+    sweeping_in_progress_ = true;
     if (!FLAG_predictable) {
       StartSweeperThreads();
     }

src/heap/spaces.cc

@@ -2569,7 +2569,8 @@ void PagedSpace::PrepareForMarkCompact() {
 
 
 intptr_t PagedSpace::SizeOfObjects() {
-  DCHECK(heap()->mark_compact_collector()->sweeping_in_progress() ||
+  DCHECK(FLAG_predictable ||
+         heap()->mark_compact_collector()->sweeping_in_progress() ||
          (unswept_free_bytes_ == 0));
   return Size() - unswept_free_bytes_ - (limit() - top());
 }