Start incremental marking in long idle notification for background tab

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 4958 matching lines @@
 bool Heap::IdleNotification(double deadline_in_seconds) {
   CHECK(HasBeenSetUp());
   double deadline_in_ms =
       deadline_in_seconds *
       static_cast<double>(base::Time::kMillisecondsPerSecond);
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_idle_notification());
   double start_ms = MonotonicallyIncreasingTimeInMs();
   double idle_time_in_ms = deadline_in_ms - start_ms;
 
+  if (idle_time_in_ms >= GCIdleTimeHandler::kMinBackgroundIdleTime) {
+    MemoryReducer::Event event;
+    event.type = MemoryReducer::kBackgroundIdleNotification;
+    event.time_ms = start_ms;
+    event.can_start_incremental_gc = incremental_marking()->IsStopped() &&
+                                     incremental_marking()->CanBeActivated();
+    memory_reducer_.NotifyBackgroundIdleNotification(event);
+  }

[Hannes Payer (out of office), 2015/07/07 07:49:34]

Let's make this block a method to keep IdleNotification small and readable.

[ulan, 2015/07/07 11:58:26]

Done.

+
   tracer()->SampleAllocation(start_ms, NewSpaceAllocationCounter(),
                              OldGenerationAllocationCounter());
 
   GCIdleTimeHandler::HeapState heap_state = ComputeHeapState();
 
   GCIdleTimeAction action =
       gc_idle_time_handler_.Compute(idle_time_in_ms, heap_state);
 
   bool result = PerformIdleTimeAction(action, heap_state, deadline_in_ms);
 
@@ skipping 1889 matching lines @@
     *object_type = "CODE_TYPE";                                                \
     *object_sub_type = "CODE_AGE/" #name;                                      \
     return true;
     CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
 #undef COMPARE_AND_RETURN_NAME
   }
   return false;
 }
 }  // namespace internal
 }  // namespace v8