Revert of Remove void** from disk_cache interface.

Revert of Remove void** from disk_cache interface. (patchset #30 id:650001 of https://codereview.chromium.org/542733002/)

Reason for revert:
Introduced memory leaks on linux asan
http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%20LSan%20Tests%20%281%29/builds/5892:
Direct leak of 80 byte(s) in 2 object(s) allocated from:
#0 0x501ccb in operator new(unsigned long) (/b/build/slave/Linux_ASan_LSan_Tests__1_/build/src/out/Release/net_unittests+0x501ccb)
#1 0x309f8d7 in disk_cache::BackendImpl::OpenNextEntryImpl(void**) net/disk_cache/blockfile/backend_impl.cc:620:5
#2 0x30a02cd in disk_cache::BackendImpl::SyncOpenNextEntry(void**, disk_cache::Entry**) net/disk_cache/blockfile/backend_impl.cc:436:17
#3 0x30d49dd in disk_cache::BackendIO::ExecuteBackendOperation() net/disk_cache/blockfile/in_flight_backend_io.cc:248:17
#4 0x2e3b0bf in Run base/callback.h:401:12
#5 0x2e3b0bf in base::debug::TaskAnnotator::RunTask(char const*, char const*, base::PendingTask const&) base/debug/task_annotator.cc:62
#6 0x2dc22fc in base::MessageLoop::RunTask(base::PendingTask const&) base/message_loop/message_loop.cc:446:3
#7 0x2dc33cc in DeferOrRunPendingTask base/message_loop/message_loop.cc:456:5
#8 0x2dc33cc in base::MessageLoop::DoWork() base/message_loop/message_loop.cc:565
#9 0x2e2361f in base::MessagePumpLibevent::Run(base::MessagePump::Delegate*) base/message_loop/message_pump_libevent.cc:232:21
#10 0x2ddd94b in base::RunLoop::Run() base/run_loop.cc:54:3
#11 0x2dc0bc4 in base::MessageLoop::Run() base/message_loop/message_loop.cc:308:3
#12 0x2e0ad90 in base::Thread::ThreadMain() base/threading/thread.cc:228:5
#13 0x2dfeaf0 in base::(anonymous namespace)::ThreadFunc(void*) base/threading/platform_thread_posix.cc:80:3
#14 0x7fa9f4e0ce99 in start_thread /build/buildd/eglibc-2.15/nptl/pthread_create.c:308

Indirect leak of 64 byte(s) in 2 object(s) allocated from:
#0 0x501ccb in operator new(unsigned long) (/b/build/slave/Linux_ASan_LSan_Tests__1_/build/src/out/Release/net_unittests+0x501ccb)
#1 0x30ebaaf in disk_cache::Rankings::GetNext(disk_cache::StorageBlock<disk_cache::RankingsNode>*, disk_cache::Rankings::List) net/disk_cache/blockfile/rankings.cc:435:5
#2 0x30a219d in disk_cache::BackendImpl::OpenFollowingEntryFromList(disk_cache::Rankings::List, disk_cache::StorageBlock<disk_cache::RankingsNode>**, disk_cache::EntryImpl**) net/disk_cache/blockfile/backend_impl.cc:1694:36
#3 0x309fa3d in disk_cache::BackendImpl::OpenNextEntryImpl(void**) net/disk_cache/blockfile/backend_impl.cc:638:11
#4 0x30a02cd in disk_cache::BackendImpl::SyncOpenNextEntry(void**, disk_cache::Entry**) net/disk_cache/blockfile/backend_impl.cc:436:17
#5 0x30d49dd in disk_cache::BackendIO::ExecuteBackendOperation() net/disk_cache/blockfile/in_flight_backend_io.cc:248:17
#6 0x2e3b0bf in Run base/callback.h:401:12
#7 0x2e3b0bf in base::debug::TaskAnnotator::RunTask(char const*, char const*, base::PendingTask const&) base/debug/task_annotator.cc:62
#8 0x2dc22fc in base::MessageLoop::RunTask(base::PendingTask const&) base/message_loop/message_loop.cc:446:3
#9 0x2dc33cc in DeferOrRunPendingTask base/message_loop/message_loop.cc:456:5
#10 0x2dc33cc in base::MessageLoop::DoWork() base/message_loop/message_loop.cc:565
#11 0x2e2361f in base::MessagePumpLibevent::Run(base::MessagePump::Delegate*) base/message_loop/message_pump_libevent.cc:232:21
#12 0x2ddd94b in base::RunLoop::Run() base/run_loop.cc:54:3
#13 0x2dc0bc4 in base::MessageLoop::Run() base/message_loop/message_loop.cc:308:3
#14 0x2e0ad90 in base::Thread::ThreadMain() base/threading/thread.cc:228:5
#15 0x2dfeaf0 in base::(anonymous namespace)::ThreadFunc(void*) base/threading/platform_thread_posix.cc:80:3
#16 0x7fa9f4e0ce99 in start_thread /build/buildd/eglibc-2.15/nptl/pthread_create.c:308

Indirect leak of 36 byte(s) in 1 object(s) allocated from:
#0 0x501ccb in operator new(unsigned long) (/b/build/slave/Linux_ASan_LSan_Tests__1_/build/src/out/Release/net_unittests+0x501ccb)
#1 0x30c0696 in AllocateData net/disk_cache/blockfile/storage_block-inl.h:179:5
#2 0x30c0696 in disk_cache::StorageBlock<disk_cache::RankingsNode>::Load() net/disk_cache/blockfile/storage_block-inl.h:121
#3 0x30e6fe9 in disk_cache::Rankings::GetRanking(disk_cache::StorageBlock<disk_cache::RankingsNode>*) net/disk_cache/blockfile/rankings.cc:586:8
#4 0x30ebd5a in disk_cache::Rankings::GetNext(disk_cache::StorageBlock<disk_cache::RankingsNode>*, disk_cache::Rankings::List) net/disk_cache/blockfile/rankings.cc:440:8
#5 0x30a219d in disk_cache::BackendImpl::OpenFollowingEntryFromList(disk_cache::Rankings::List, disk_cache::StorageBlock<disk_cache::RankingsNode>**, disk_cache::EntryImpl**) net/disk_cache/blockfile/backend_impl.cc:1694:36
#6 0x309fa3d in disk_cache::BackendImpl::OpenNextEntryImpl(void**) net/disk_cache/blockfile/backend_impl.cc:638:11
#7 0x30a02cd in disk_cache::BackendImpl::SyncOpenNextEntry(void**, disk_cache::Entry**) net/disk_cache/blockfile/backend_impl.cc:436:17
#8 0x30d49dd in disk_cache::BackendIO::ExecuteBackendOperation() net/disk_cache/blockfile/in_flight_backend_io.cc:248:17
#9 0x2e3b0bf in Run base/callback.h:401:12
#10 0x2e3b0bf in base::debug::TaskAnnotator::RunTask(char const*, char const*, base::PendingTask const&) base/debug/task_annotator.cc:62
#11 0x2dc22fc in base::MessageLoop::RunTask(base::PendingTask const&) base/message_loop/message_loop.cc:446:3
#12 0x2dc33cc in DeferOrRunPendingTask base/message_loop/message_loop.cc:456:5
#13 0x2dc33cc in base::MessageLoop::DoWork() base/message_loop/message_loop.cc:565
#14 0x2e2361f in base::MessagePumpLibevent::Run(base::MessagePump::Delegate*) base/message_loop/message_pump_libevent.cc:232:21
#15 0x2ddd94b in base::RunLoop::Run() base/run_loop.cc:54:3
#16 0x2dc0bc4 in base::MessageLoop::Run() base/message_loop/message_loop.cc:308:3
#17 0x2e0ad90 in base::Thread::ThreadMain() base/threading/thread.cc:228:5
#18 0x2dfeaf0 in base::(anonymous namespace)::ThreadFunc(void*) base/threading/platform_thread_posix.cc:80:3
#19 0x7fa9f4e0ce99 in start_thread /build/buildd/eglibc-2.15/nptl/pthread_create.c:308

Original issue's description:
> Remove void** from disk_cache interface.
>
> Enumeration and iteration were passing around void**. With this CL, we
> instead use an Iterator object.
>
> R=clamy@chromium.org,jkarlin@chromium.org,jsbell@chromium.org
> BUG=413644
>
> Committed: https://crrev.com/732c8306d4864296511e7a3a252724b1bb34c342
> Cr-Commit-Position: refs/heads/master@{#295659}

TBR=clamy@chromium.org,jkarlin@chromium.org,jsbell@chromium.org,rvargas@chromium.org,pasko@chromium.org,piman@chromium.org,michaeln@chromium.org,cbentzel@chromium.org,gavinp@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=413644
Committed: https://crrev.com/a3b755859b3113c74df16939f124bc42464092b1
Cr-Commit-Position: refs/heads/master@{#295677}

[vasilii, 2014-09-19 08:18:32]

Created Revert of Remove void** from disk_cache interface.

[commit-bot: I haz the power, 2014-09-19 08:19:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/585833002/1

[commit-bot: I haz the power, 2014-09-19 08:20:29]

Committed patchset #1 (id:1) as 719e9be75a622ce12ce56cfc1d94825fb107b64e

[commit-bot: I haz the power, 2014-09-19 08:21:13]

Patchset 1 (id:??) landed as
https://crrev.com/a3b755859b3113c74df16939f124bc42464092b1
Cr-Commit-Position: refs/heads/master@{#295677}