Make the profile buffer larger in third_party/tcmalloc/chromium.

third_party/tcmalloc/chromium/src/heap-profiler.cc

 // Copyright (c) 2005, Google Inc.
 // 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
@@ skipping 131 matching lines @@
 static LowLevelAlloc::Arena *heap_profiler_memory;
 
 static void* ProfilerMalloc(size_t bytes) {
   return LowLevelAlloc::AllocWithArena(bytes, heap_profiler_memory);
 }
 static void ProfilerFree(void* p) {
   LowLevelAlloc::Free(p);
 }
 
 // We use buffers of this size in DoGetHeapProfile.
-static const int kProfileBufferSize = 1 << 20;
+// The size is 1 << 20 in the original google-perftools.  Changed it to
+// 5 << 20 since larger buffers are requried for deeper profiling in Chromium.

[jar (doing other things), 2011/12/22 16:02:09]

Could you provide a comment that makes it clear when this amount of memory is
allocated and used? 1 Meg is already a lot, and 5M is of course a whole lot.

I started to read the code to try to track this down, but IMO, it would be nice
to have the comment here.

[Dai Mikurube (NOT FULLTIME), 2011/12/26 03:58:26]

Done.

+static const int kProfileBufferSize = 5 << 20;
 
 // This is a last-ditch buffer we use in DumpProfileLocked in case we
 // can't allocate more memory from ProfilerMalloc.  We expect this
 // will be used by HeapProfileEndWriter when the application has to
 // exit due to out-of-memory.  This buffer is allocated in
 // HeapProfilerStart.  Access to this must be protected by heap_lock.
 static char* global_profiler_buffer = NULL;
 
 
 //----------------------------------------------------------------------
@@ skipping 394 matching lines @@
 
 // class used for finalization -- dumps the heap-profile at program exit
 struct HeapProfileEndWriter {
   ~HeapProfileEndWriter() { HeapProfilerDump("Exiting"); }
 };
 
 // We want to make sure tcmalloc is up and running before starting the profiler
 static const TCMallocGuard tcmalloc_initializer;
 REGISTER_MODULE_INITIALIZER(heapprofiler, HeapProfilerInit());
 static HeapProfileEndWriter heap_profile_end_writer;