Cleanup leftover code and suppression from M47 ffmpeg roll.

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 # running overnight and removing outdated bugs/suppressions.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 3332 matching lines @@
    fun:calloc
    fun:pthread_setspecific
    ...
    fun:_ZN3gpu22InProcessCommandBuffer21InitializeOnGpuThreadERKNS0_27InitializeOnGpuThreadParamsE
 }
 {
    bug_441333
    Memcheck:Uninitialized
    fun:av_packet_unpack_dictionary
    fun:add_metadata_from_side_data
-   ...
 }
 {
    bug_448700_a
    Memcheck:Leak
    fun:_Znw*
    ...
    fun:_ZN10extensions11ApiTestBase15RegisterModulesEv
    fun:_ZN10extensions11ApiTestBase5SetUpEv
 }
 {
@@ skipping 283 matching lines @@
 }
 {
    bug_525328
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN9__gnu_cxx13new_allocatorISt13_Rb_tree_nodeISt4pairIKSsPN3net20URLRequestJobFactory15ProtocolHandlerEEEE8allocateEmPKv
    fun:_ZNSt8_Rb_treeISsSt4pairIKSsPN3net20URLRequestJobFactory15ProtocolHandlerEESt10_Select1stIS6_ESt4lessISsESaIS6_EE11_M_get_nodeEv
    fun:_ZNSt8_Rb_treeISsSt4pairIKSsPN3net20URLRequestJobFactory15ProtocolHandlerEESt10_Select1stIS6_ESt4lessISsESaIS6_EE14_M_create_nodeIJS6_EEEPSt13_Rb_tree_nodeIS6_EDpOT_
    fun:_ZNSt8_Rb_treeISsSt4pairIKSsPN3net20URLRequestJobFactory15ProtocolHandlerEESt10_Select1stIS6_ESt4lessISsESaIS6_EE10_M_insert_IS6_EESt17_Rb_tree_iteratorIS6_EPKSt18_Rb_tree_node_baseSI_OT_
 }