Adjust GC tracing: add a flag to ignore scavenger traces and print total GC time in verbose mode.

src/heap.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2037 matching lines @@
 
   // Object counts and used memory by InstanceType
   size_t object_counts_[OBJECT_STATS_COUNT];
   size_t object_counts_last_time_[OBJECT_STATS_COUNT];
   size_t object_sizes_[OBJECT_STATS_COUNT];
   size_t object_sizes_last_time_[OBJECT_STATS_COUNT];
 
   // Maximum GC pause.
   int max_gc_pause_;
 
+  // Total time spent in GC.
+  int total_gc_time_ms_;
+
   // Maximum size of objects alive after GC.
   intptr_t max_alive_after_gc_;
 
   // Minimal interval between two subsequent collections.
   int min_in_mutator_;
 
   // Size of objects alive after last GC.
   intptr_t alive_after_last_gc_;
 
   double last_gc_end_timestamp_;
@@ skipping 697 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_