[MemSheriff] Enable tcmalloc for valgrind again.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 2266 matching lines @@
         # Without this flag, JS code causes false positive reports from MSan.
         'v8_target_arch': 'arm64',
       }],
 
       # On valgrind bots, override the optimizer settings so we don't inline too
       # much and make the stacks harder to figure out.
       #
       # TODO(rnk): Kill off variables that no one else uses and just implement
       # them under a build_for_tool== condition.
       ['build_for_tool=="memcheck" or build_for_tool=="tsan"', {
-
-        # tcmalloc causes Valgrind failures. Discussion in crrev.com/1642383002.
-        'use_allocator%': 'none',
-
         # gcc flags
         'mac_debug_optimization': '1',
         'mac_release_optimization': '1',
         'release_optimize': '1',
         'no_gc_sections': 1,
         'debug_extra_cflags': '-g -fno-inline -fno-omit-frame-pointer '
                               '-fno-builtin -fno-optimize-sibling-calls',
         'release_extra_cflags': '-g -fno-inline -fno-omit-frame-pointer '
                                 '-fno-builtin -fno-optimize-sibling-calls',
 
@@ skipping 4099 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }