linux: TCMalloc-based C++ heap profiler.

base/base.gyp

Index: base/base.gyp
diff --git a/base/base.gyp b/base/base.gyp
index 31d9d49995f9c2944ea094d474093fcb070e3e04..52ffe09de0544be8f35db73a91e7a97f53452609 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -376,9 +376,6 @@
       ],
       'conditions': [
         [ 'OS == "linux" or OS == "freebsd"', {
-            'variables' : {
-              'linux_use_tcmalloc%': 0,
-            },
             'sources/': [ ['exclude', '_(mac|win|chromeos)\\.cc$'],
                           ['exclude', '\\.mm?$' ] ],
             'conditions': [