Fix memory leaks in TopSites.

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 # running overnight and removing outdated bugs/suppressions.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 879 matching lines @@
    fun:net::HttpCache::Transaction::DoLoop
    fun:net::HttpCache::Transaction::Start
    fun:URLRequestHttpJob::StartTransaction
    fun:URLRequestHttpJob::OnCanGetCookiesCompleted
    fun:URLRequestHttpJob::AddCookieHeaderAndStart
    fun:URLRequestHttpJob::Start
    fun:URLRequest::StartJob
    fun:URLRequest::Start
    fun:HTTPTestServer::StartGETRequest
 }
-{
-   bug_50103_a
-   Heapcheck:Leak
-   fun:Value::CreateNullValue
-   fun:history::TopSites::AddBlacklistedURL
-   fun:history::TopSitesTest_*_Test::TestBody
-}
-{
-   bug_50103_b
-   Heapcheck:Leak
-   fun:Value::CreateIntegerValue
-   fun:history::TopSites::AddPinnedURL
-   fun:history::TopSitesTest_PinnedURLs_Test::TestBody
-}