Linux: add gyp flag for enabling tcmalloc.

base/base.gyp

 # Copyright (c) 2009 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'includes': [
     '../build/common.gypi',
@@ skipping 347 matching lines @@
         'include_dirs': [
           '..',
         ],
       },
       # These warnings are needed for the files in third_party\dmg_fp.
       'msvs_disabled_warnings': [
         4244, 4554, 4018, 4102,
       ],
       'conditions': [
         [ 'OS == "linux"', {
+            'variables' : {
+              'linux_use_tcmalloc%': 0,
+            },
             'sources/': [ ['exclude', '_(mac|win|chromeos)\\.cc$'],
                           ['exclude', '\\.mm?$' ] ],
             'sources!': [
               # Linux has an implementation of idle_timer that depends
               # on XScreenSaver, but it's unclear if we want it yet,
               # so use idle_timer_none.cc instead.
               'idle_timer.cc',
             ],
             'conditions': [
               [ 'chromeos==1', {
                   'sources/': [ ['include', '_chromeos\\.cc$'] ]
                 },
               ],
+              [ 'linux_use_tcmalloc==1', {
+                  'dependencies': [
+                    '../third_party/tcmalloc/tcmalloc.gyp:tcmalloc',
+                  ],
+                },
+              ],
             ],
             'dependencies': [
               '../build/util/build_util.gyp:lastchange',
               '../build/linux/system.gyp:gtk',
               '../build/linux/system.gyp:nss',
             ],
             'cflags': [
               '-Wno-write-strings',
             ],
             'link_settings': {
@@ skipping 446 matching lines @@
                 '<@(_outputs)',
               ],
               'message': 'Generating version information',
             },
           ],
         },
       ],
     }],
   ],
 }