Remove duplicate suppression by reverting r54068.

tools/valgrind/memcheck/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 # running overnight and removing outdated bugs/suppressions.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 3573 matching lines @@
    fun:_ZN18ProfileSyncService*
    fun:_ZN22ProfileSync*
    ...
    fun:*GetProfileSyncServiceEv
    fun:_ZN7Profile16IsSyncAccessibleEv
    fun:_ZN7Browser31UpdateCommandsForFullscreenModeEb
    fun:_ZN7Browser16InitCommandStateEv
    fun:_ZN7Browser*ENS_4TypeEP7Profile
 }
 {
-   bug_50579
-   Memcheck:Leak
-   fun:_Znw*
-   fun:_ZN3net14DnsReloadTimer7ExpiredEv
-   fun:_ZN3net24DnsReloadTimerHasExpiredEv
-   fun:_ZN3net22SystemHostResolverProcERKSsNS_13AddressFamilyEiPNS_11AddressListEPi
-   fun:_ZN3net15ResolveAddrInfoEPNS_16HostResolverProcERKSsNS_13AddressFamilyEiPNS_11AddressListEPi
-   fun:_ZN3net16HostResolverImpl3Job8DoLookupEv
-   fun:_Z16DispatchToMethodIN3net16HostResolverImpl3JobEMS2_FvvEEvPT_T0_RK6Tuple0
-   fun:_ZN14RunnableMethodIN3net16HostResolverImpl3JobEMS2_FvvE6Tuple0E3RunEv
-}
-{
    bug_50583
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN64_GLOBAL__N_net_base_cookie_monster_unittest.cc_00000000_C9F6D94420AddKeyedCookieToListERKSsS1_RKN4base4TimeEPSt6vectorISt4pairISsPN3net13CookieMonster15CanonicalCookieEESaISC_EE
    fun:_ZN3net55CookieMonsterTest_DontImportDuplicateCreationTimes_Test8TestBodyEv
 }
 {
    bug_50630
    Memcheck:Value4
    fun:modp_b64_encode
    fun:_ZN4base12Base64EncodeERKSsPSs
    fun:_Z24ConvertSkBitmapToDataURLRK8SkBitmap
    fun:_ZN22InternetOptionsHandler10GetNetworkERKSsRK8SkBitmapS1_bbib
    ...
    fun:_ZN22InternetOptionsHandler18GetLocalizedValuesEP15DictionaryValue
    fun:_ZN9OptionsUI23AddOptionsPageUIHandlerEP15DictionaryValueP20OptionsPageUIHandler
    fun:_ZN9OptionsUIC1EP11TabContents
 }