Fix leak in PrerenderResourceHandlerTest.

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 # running overnight and removing outdated bugs/suppressions.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 3550 matching lines @@
    fun:_ZN3net17HttpStreamRequest7RunLoopEi
    fun:_ZN3net17HttpStreamRequest13StartInternalEPKNS_15HttpRequestInfoEPNS_9SSLConfigEPNS_9ProxyInfoERKNS_11BoundNetLogE
    fun:_ZN3net17HttpStreamRequest5StartEPKNS_15HttpRequestInfoEPNS_9SSLConfigEPNS_9ProxyInfoEPNS_13StreamRequest8DelegateERKNS_11BoundNetLogE
    fun:_ZN3net17HttpStreamFactory13RequestStreamEPKNS_15HttpRequestInfoEPNS_9SSLConfigEPNS_9ProxyInfoEPNS_18HttpNetworkSessionEPNS_13StreamRequest8DelegateERKNS_11BoundNetLogE
    fun:_ZN3net22HttpNetworkTransaction14DoCreateStreamEv
    fun:_ZN3net22HttpNetworkTransaction6DoLoopEi
    fun:_ZN3net22HttpNetworkTransaction5StartEPKNS_15HttpRequestInfoEP14CallbackRunnerI6Tuple1IiEERKNS_11BoundNetLogE
    fun:_ZN3net9HttpCache11Transaction13DoSendRequestEv
 }
 {
-   bug_69414
-   Memcheck:Leak
-   fun:_Znw*
-   fun:_ZN28PrerenderResourceHandlerTestC2Ev
-}
-{
    Bug_69919
    Memcheck:Leak
    fun:calloc
    ...
    fun:_ZN3gfx15OSMesaGLContext10InitializeEjPNS_9GLContextE
    fun:_ZN3gfx9GLContext24CreateOffscreenGLContextEPS0_
    fun:*InitializeGLContextEv
 }
 {
    Bug_69934_a
@@ skipping 39 matching lines @@
    fun:PR_CallOnce
    fun:ssl_InitSessionCacheLocks
    fun:lock_cache
    fun:ssl_LookupSID
    fun:ssl2_BeginClientHandshake
    fun:ssl_Do1stHandshake
    fun:SSL_ForceHandshake
    fun:_ZN3net18SSLClientSocketNSS11DoHandshakeEv
    fun:_ZN3net18SSLClientSocketNSS15DoHandshakeLoopEi
 }