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

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

Index: third_party/tcmalloc/chromium/src/heap-profiler.cc
diff --git a/third_party/tcmalloc/chromium/src/heap-profiler.cc b/third_party/tcmalloc/chromium/src/heap-profiler.cc
index fd0faa33fdf486dca69ee09f51f9254b42373339..4df8321f3943fb5067ffbb6bcf3cb661e6251b29 100644
--- a/third_party/tcmalloc/chromium/src/heap-profiler.cc
+++ b/third_party/tcmalloc/chromium/src/heap-profiler.cc
@@ -149,7 +149,11 @@ static void ProfilerFree(void* 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 a larger buffer is requried for deeper profiling in Chromium.
+// The buffer is allocated only when the environment variable HEAPPROFILE is
+// specified to dump heap information.
+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