Add bug 68516 to the list of known crashes.

chrome/test/data/reliability/known_crashes.txt

Index: chrome/test/data/reliability/known_crashes.txt
===================================================================
--- chrome/test/data/reliability/known_crashes.txt	(revision 71052)
+++ chrome/test/data/reliability/known_crashes.txt	(working copy)
@@ -140,3 +140,8 @@
 # 66795
 PREFIX : webkit_glue::resourcefetcher::didfail___webkit_glue::weburlloaderimpl::context::oncompletedrequest___resourcedispatcher::onrequestcomplete___ipc::messagewithtuple<tuple4<int,urlrequeststatus,std::basic_string<char,std::char_traits<char>,std::allocator<char> >,base::time> >::dispatch<resourcedispatcher,void (__thiscall resourcedispatcher::*)(int,urlrequeststatus const &,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,base::time const &)>___resourcedispatcher::dispatchmessagew___resourcedispatcher::onmessagereceived___childthread::onmessagereceived___runnablemethod<selectfiledialogimpl,void (__thiscall selectfiledialogimpl::*)(selectfiledialogimpl::executeselectparams const &),tuple1<selectfiledialogimpl::executeselectparams> >::run___messageloop::runtask___messageloop::dowork___base::messagepumpdefault::run___messageloop::runinternal___messageloop::run___renderermain
 PREFIX : webkit_glue::resourcefetcher::didfail___webkit_glue::weburlloaderimpl::context::oncompletedrequest___resourcedispatcher::onrequestcomplete___ipc::messagewithtuple<tuple4<int,urlrequeststatus,std::basic_string<char,std::char_traits<char>,std::allocator<char> >,base::time> >::dispatch<resourcedispatcher,resourcedispatcher,void (__thiscall resourcedispatcher::*)(int,urlrequeststatus const &,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,base::time const &)>___resourcedispatcher::dispatchmessagew___resourcedispatcher::onmessagereceived___childthread::onmessagereceived___runnablemethod<profilewriter,void (__thiscall profilewriter::*)(gurl const &),tuple1<gurl> >::run___messageloop::runtask___messageloop::dowork___base::messagepumpdefault::run___messageloop::runinternal___messageloop::run___renderermain
+
+# 68516
+PREFIX : tcmalloc::threadcache::releasetocentralcache___tcmalloc::threadcache::scavenge___tcmalloc::threadcache::deallocate___`anonymous namespace'::do_free_with_callback___operator delete[]___webcore::cssmutablestyledeclaration::`scalar deleting destructor'
+PREFIX : tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___malloc___wtf::fastmalloc___webcore::renderstyle::setbordertopcolor___webcore::cssstyleselector::applyproperty___webcore::cssstyleselector::applydeclarations<0>___webcore::cssstyleselector::styleforelement
+PREFIX : tcmalloc::threadcache::allocate___`anonymous namespace'::do_malloc___malloc___wtf::fastmalloc___webcore::renderstyle::create___webcore::cssstyleselector::styleforelement___webcore::node::styleforrenderer___webcore::node::createrendererifneeded___webcore::element::attach