To be precise, Valgrind has been obsoleted by the combination of ASan, LSan and MSan.
If we are talking about RunningOnValgrind() calls in Chromium code, we can simply drop most of them. Perhaps there are some places where the code is too slow even under compiler tools (i.e. the sanitizers), but in those cases we'd better use #ifdef directives instead.

Here's a patch for //base:
https://chromium-review.googlesource.com/c/chromium/src/+/805894

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1a70fddf3c4a571e00fabad8404fe54e0c338520

commit 1a70fddf3c4a571e00fabad8404fe54e0c338520
Author: Mostyn Bramley-Moore <mostynb@vewd.com>
Date: Mon Dec 04 21:52:02 2017

remove valgrind checks from //sandbox/linux

We have not supported valgrind for some time (it was never ported to
the GN build IIUC, and has been obsoleted by ASan/MSan/TSan).

Followup to https://chromium-review.googlesource.com/c/chromium/src/+/778881

BUG=791518

Change-Id: I3a03f033263e6477eddcc683b986635b6ff2c963
Reviewed-on: https://chromium-review.googlesource.com/805994
Commit-Queue: Mostyn Bramley-Moore <mostynb@vewd.com>
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521472}
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/seccomp-bpf/sandbox_bpf.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/seccomp-bpf/sandbox_bpf_test_runner.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/seccomp-bpf/sandbox_bpf_test_runner.h
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/seccomp-bpf/syscall.h
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/services/credentials.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/services/namespace_utils.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/services/syscall_wrappers.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/services/syscall_wrappers_unittest.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/services/thread_helpers_unittests.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/syscall_broker/broker_host.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/syscall_broker/broker_process_unittest.cc
[modify] https://crrev.com/1a70fddf3c4a571e00fabad8404fe54e0c338520/sandbox/linux/tests/unit_tests.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b304319fce3158845025e9ae92aa7a61d9debab0

commit b304319fce3158845025e9ae92aa7a61d9debab0
Author: Mostyn Bramley-Moore <mostynb@vewd.com>
Date: Wed Dec 06 08:36:19 2017

remove valgrind checks from //gpu

We have not supported valgrind for some time (it was never ported to
the GN build IIUC, and has been obsoleted by ASan/MSan/TSan).

BUG=791518

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I0948b46f523be2a28894306b9377646d111c22a8
Reviewed-on: https://chromium-review.googlesource.com/809131
Reviewed-by: Antoine Labour <piman@chromium.org>
Reviewed-by: Abhishek Arya <inferno@chromium.org>
Commit-Queue: Mostyn Bramley-Moore <mostynb@vewd.com>
Cr-Commit-Position: refs/heads/master@{#522042}
[modify] https://crrev.com/b304319fce3158845025e9ae92aa7a61d9debab0/gpu/ipc/service/gpu_init.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a180eb306fc8919cbba92f60e7f468e6cfc93e4f

commit a180eb306fc8919cbba92f60e7f468e6cfc93e4f
Author: Mostyn Bramley-Moore <mostynb@vewd.com>
Date: Wed Dec 06 08:40:48 2017

remove valgrind checks from //content

We have not supported valgrind for some time (it was never ported to
the GN build IIUC, and has been obsoleted by ASan/MSan/TSan).

BUG=791518

Change-Id: Id24289347d0811ed51a0b9ac036c746ef18bf75f
Reviewed-on: https://chromium-review.googlesource.com/809426
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Mostyn Bramley-Moore <mostynb@vewd.com>
Cr-Commit-Position: refs/heads/master@{#522045}
[modify] https://crrev.com/a180eb306fc8919cbba92f60e7f468e6cfc93e4f/content/common/child_process_host_impl.cc
[modify] https://crrev.com/a180eb306fc8919cbba92f60e7f468e6cfc93e4f/content/test/blink_test_environment.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a302a709a891b553e8b4e0a2973a32a1c9e74ab2

commit a302a709a891b553e8b4e0a2973a32a1c9e74ab2
Author: Mostyn Bramley-Moore <mostynb@vewd.com>
Date: Wed Dec 06 09:28:38 2017

remove valgrind checks from //components/nacl/zygote

We have not supported valgrind for some time (it was never ported to
the GN build IIUC, and has been obsoleted by ASan/MSan/TSan).

BUG=791518

Change-Id: I9d6f5125de817b9334b295a8a78589004bb08294
Reviewed-on: https://chromium-review.googlesource.com/809132
Commit-Queue: Mostyn Bramley-Moore <mostynb@vewd.com>
Reviewed-by: Mark Seaborn <mseaborn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522051}
[modify] https://crrev.com/a302a709a891b553e8b4e0a2973a32a1c9e74ab2/components/nacl/zygote/nacl_fork_delegate_linux.cc
[modify] https://crrev.com/a302a709a891b553e8b4e0a2973a32a1c9e74ab2/components/nacl/zygote/nacl_fork_delegate_linux.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529

commit d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529
Author: Mostyn Bramley-Moore <mostynb@vewd.com>
Date: Wed Dec 06 19:13:21 2017

remove valgrind checks from //base

We have not supported valgrind for some time (it was never ported to
the GN build IIUC, and has been obsoleted by ASan/MSan/TSan).

BUG=791518, 431702 

Change-Id: Ibfad450ee2973cf5916986559f543aced08e108a
Reviewed-on: https://chromium-review.googlesource.com/805894
Reviewed-by: danakj <danakj@chromium.org>
Commit-Queue: Mostyn Bramley-Moore <mostynb@vewd.com>
Cr-Commit-Position: refs/heads/master@{#522154}
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/BUILD.gn
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/allocator/README.md
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/command_line.h
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/debug/proc_maps_linux_unittest.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/message_loop/message_loop_io_posix_unittest.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/metrics/field_trial_unittest.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/observer_list_unittest.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/process/launch.h
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/process/launch_posix.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/process/process_posix.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/process/process_util_unittest.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/security_unittest.cc
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/test/android/javatests/src/org/chromium/base/test/util/ScalableTimeout.java
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/test/test_timeouts.h
[modify] https://crrev.com/d0ecd6a5404c1f7b2b3b9ed0d6bad66fdbceb529/base/tools_sanity_unittest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/699c531bd1824a34eb2032c969e197add2dbd166

commit 699c531bd1824a34eb2032c969e197add2dbd166
Author: Mostyn Bramley-Moore <mostynb@vewd.com>
Date: Tue May 01 10:48:09 2018

remove references to specific memory tools from //net/

We have not supported valgrind for some time (it was never ported to
the GN build IIUC, and has been obsoleted by ASan/MSan/TSan).  While
we're at it, let's use general terminology instead of referring to
specific tools.

Bug:  46925 ,791518, 16076 
Change-Id: I294788bf31621f2373ce3bf5d6a4036e056d2428
Reviewed-on: https://chromium-review.googlesource.com/1029861
Commit-Queue: Mostyn Bramley-Moore <mostynb@vewd.com>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: Alexander Potapenko <glider@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555023}
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/cert/nss_cert_database_unittest.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/proxy_resolution/dhcp_pac_file_fetcher_win_unittest.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/proxy_resolution/proxy_config_service_linux.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/quic/core/quic_crypto_server_stream_test.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/quic/core/quic_server_session_base_test.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/socket/ssl_server_socket_unittest.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/spdy/chromium/spdy_network_transaction_unittest.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/spdy/chromium/spdy_session_unittest.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/spdy/core/hpack/hpack_decoder_adapter_test.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/ssl/channel_id_service_unittest.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/ssl/ssl_client_session_cache_unittest.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/third_party/http2/hpack/decoder/hpack_entry_type_decoder.h
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/third_party/http2/hpack/decoder/hpack_string_decoder.h
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/third_party/http2/hpack/decoder/hpack_varint_decoder.h
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/tools/dns_fuzz_stub/dns_fuzz_stub.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/tools/quic/quic_client_test.cc
[modify] https://crrev.com/699c531bd1824a34eb2032c969e197add2dbd166/net/websockets/websocket_inflater_test.cc