Rewrite BufferedDataSource tests to use real BufferedResourceLoader objects.

tools/valgrind/memcheck/suppressions.txt

 # There are four 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 # running overnight and removing outdated bugs/suppressions.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 4676 matching lines @@
    fun:_ZN10URLFetcher4Core21OnCompletedURLRequestEN4base9TimeDeltaE
 }
 {
    bug_100777
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN12_GLOBAL__N_119MakeContextDelegateI16CrxUpdateServiceNS1_13UpdateContextEEEPN10URLFetcher8DelegateEPT_PT0_
    fun:_ZN16CrxUpdateService19ProcessPendingItemsEv
 }
 {
-   bug_100914a
+   bug_100914
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN12webkit_media18BufferedDataSource20CreateResourceLoaderEll
-   fun:_ZN12webkit_media18BufferedDataSource24HttpInitialStartCallbackEi
-}
-{
-   bug_100914b
-   Memcheck:Leak
-   fun:_Znw*
-   fun:_ZN12webkit_media18BufferedDataSource20CreateResourceLoaderEll
-   fun:_ZN12webkit_media18BufferedDataSource14InitializeTaskEv
 }
 {
    bug_100916
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN6WebKit19WebWorkerClientImpl24createWorkerContextProxyEPN7WebCore6WorkerE
    ...
    fun:_ZN7WebCore6WorkerC1EPNS_22ScriptExecutionContextE
    fun:_ZN7WebCore6Worker6createEPNS_22ScriptExecutionContextERKN3WTF6StringERi
    fun:_ZN7WebCore8V8Worker19constructorCallbackERKN2v89ArgumentsE
@@ skipping 578 matching lines @@
    obj:/lib/libselinux.so.1
    obj:/lib/libselinux.so.1
 }
 {
    bug_todo_grep
    Memcheck:Leak
    fun:malloc
    obj:/bin/grep
    obj:/bin/grep
 }