[NOT TO COMMIT!] Merge Chromium-specific changes in tcmalloc thru. the original gperftools r136.

third_party/tcmalloc/chromium/src/packed-cache-inl.h

Index: third_party/tcmalloc/chromium/src/packed-cache-inl.h
diff --git a/third_party/tcmalloc/chromium/src/packed-cache-inl.h b/third_party/tcmalloc/chromium/src/packed-cache-inl.h
index 77f42b6b31990bbec6efecc2c18eaa233d788ef3..36a24a338aedabd79142dfca59319a8ed2dadab6 100644
--- a/third_party/tcmalloc/chromium/src/packed-cache-inl.h
+++ b/third_party/tcmalloc/chromium/src/packed-cache-inl.h
@@ -139,7 +139,9 @@ class PackedCache {
   // Decrease the size map cache if running in the small memory mode.
   static const int kHashbits = 12;
 #else
-  static const int kHashbits = 16;
+  // We don't want the hash map to occupy 512K memory at Chromium, so
+  // kHashbits is decreased from 16 to 12.
+  static const int kHashbits = 12;
 #endif
   static const int kValuebits = 7;
   static const bool kUseWholeKeys = kKeybits + kValuebits <= 8 * sizeof(T);