Fix leak in pnacl translation cache and remove check suppressions

tools/heapcheck/suppressions.txt

 # There are three kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 1858 matching lines @@
    fun:~MirrorWindowCreator
    fun:operator
    fun:~scoped_ptr_impl
    fun:~scoped_ptr
    fun:ash::internal::DisplayManager::UpdateDisplays
    fun:ash::internal::DisplayManager::OnNativeDisplaysChanged
    fun:ash::test::DisplayManagerTestApi::UpdateDisplay
    fun:ash::test::AshTestBase::UpdateDisplay
    fun:ash::internal::MirrorWindowControllerTest_MirrorCursor_Test::TestBody
 }
-{
-   bug_245092a
-   Heapcheck:Leak
-   ...
-   fun:disk_cache::MemBackendImpl::CreateBackend
-   fun:disk_cache::CreateCacheBackend
-   fun:pnacl_cache::PNaClTranslationCache::Init
-   fun:pnacl_cache::PNaClTranslationCache::InitWithMemBackend
-   fun:pnacl_cache::PNaClTranslationCache::InitCache
-}
-{
-   bug_245092b
-   Heapcheck:Leak
-   ...
-   fun:disk_cache::Mem*
-   ...
-   fun:pnacl_cache::PNaClTranslationCacheWriteEntry::DispatchNext
-   fun:pnacl_cache::PNaClTranslationCacheWriteEntry::OpenEntry
-   fun:pnacl_cache::PNaClTranslationCacheWriteEntry::Cache
-   fun:pnacl_cache::PNaClTranslationCache::StoreNexe
-}
-{
-   bug_245092c
-   Heapcheck:Leak
-   fun:std::basic_string::_Rep::_S_create
-   fun:std::basic_string::basic_string
-   fun:__gnu_cxx::__normal_iterator::base
-   fun:__gnu_cxx::operator!=
-}
-{
-   bug_245092d
-   Heapcheck:Leak
-   fun:std::basic_string::_Rep::_S_create
-   fun:std::basic_string::basic_string
-   fun:testing::TestResult::HasFatalFailure
-   fun:shadow_index
-}