Revert of Linux: Disable DBus auto-launch

Revert of Linux: Disable DBus auto-launch (patchset #1 id:1 of https://codereview.chromium.org/2861163002/ )

Reason for revert:
Speculative revert -- the TSan bots have been reporting a data race when setting Envvars (in this case, appending to the python path to start a websocket server). The race appeared immediately after this patch landed, so it may be legitimate. Reverting this to see if it clears the failures up; if so, we'll probably just have to serialize the calls to setenv.

Filed crbug.com/719633 for this as well.

Original issue's description:
> Linux: Disable DBus auto-launch
> 
> This is a workaround (ETA ~ 2-3 years) for libdbus not being multi-threading
> friendly and causing random hangs when running chrome outside of Linux
> desktop environments.
> 
> Background:
> -----------
> Typically, Linux desktop environments set the DBUS_SESSION_BUS_ADDRESS
> environment variable. This variable allows the dbus client library to
> directly connect to the existing bus, which is started by the desktop
> environment or systemd.
> When this variable is missing, the dbus client library will fallback
> to auto-launch mode [1], which causes 4 nested fork() + exec() calls.
> Doing this has two problems: (i) slows down startup; (ii) can hang
> the browser if the fork() happens while another thread is in a malloc()
> (Chrome's tcmalloc has no at-fork handlers).
> This situation (no env variable) is very common in test scenarios
> (browsertests, chromedriver, etc).
> 
> Change introduced by this CL:
> -----------------------------
> This CL sets the bus address env variable to "disabled:" if not set.
> This effectively shuts down the dbus auto-launch. If necessary, this
> behavior can be restored by setting, before launching chrome,
> DBUS_SESSION_BUS_ADDRESS="autolaunch:" .
> This workaround will be necessary until libdbus and gspawn are fixed
> to be multi-threading friendly [2,3] and that fix rolls into the
> various distributions.
> The change is introduced in the main embedder rather than in the
> google-chrome wrapper, as several binaries can be affected by this,
> for instance:
> - browser tests (http://crbug.com/693668)
> - chrome --headless
> - webdriver/selenium which seem to directly invoke "chrome"
>    see https://github.com/SeleniumHQ/docker-selenium/issues/87
> 
> [1] https://dbus.freedesktop.org/doc/dbus-launch.1.html
> [2] https://bugs.freedesktop.org/show_bug.cgi?id=100843
> [3] https://bugs.chromium.org/p/chromedriver/issues/detail?id=1699
> 
> BUG=715658, 695643, 713947
> TEST=strace -ff -o trace chrome; grep dbus-launch trace*
> 
> Review-Url: https://codereview.chromium.org/2861163002
> Cr-Commit-Position: refs/heads/master@{#469987}
> Committed: https://chromium.googlesource.com/chromium/src/+/8511820ec8280caacbd4f81f3ecd13b6c61681b0

TBR=satorux@google.com,thestig@chromium.org,jam@chromium.org,satorux@chromium.org,primiano@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=715658, 695643, 713947
Review-Url: https://codereview.chromium.org/2869843003
Cr-Commit-Position: refs/heads/master@{#470059}
Committed: https://chromium.googlesource.com/chromium/src/+/1e78cb7863da28bb3411286cdbcc4fb4510ce173

[iclelland, 2017-05-08 18:40:10]

The CQ bit was checked by iclelland@chromium.org

[iclelland, 2017-05-08 18:40:11]

Created Revert of Linux: Disable DBus auto-launch

[commit-bot: I haz the power, 2017-05-08 18:41:09]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-08 18:41:42]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1494268810812900, "parent_rev":
"832d8b7c8aff004eb7480fd0d20ce0508b24d7f4", "commit_rev":
"1e78cb7863da28bb3411286cdbcc4fb4510ce173"}

[commit-bot: I haz the power, 2017-05-08 18:41:51]

Description was changed from

==========
Revert of Linux: Disable DBus auto-launch (patchset #1 id:1 of
https://codereview.chromium.org/2861163002/ )

Reason for revert:
Speculative revert -- the TSan bots have been reporting a data race when setting
Envvars (in this case, appending to the python path to start a websocket
server). The race appeared immediately after this patch landed, so it may be
legitimate. Reverting this to see if it clears the failures up; if so, we'll
probably just have to serialize the calls to setenv.

Filed crbug.com/719633 for this as well.

Original issue's description:
> Linux: Disable DBus auto-launch
> 
> This is a workaround (ETA ~ 2-3 years) for libdbus not being multi-threading
> friendly and causing random hangs when running chrome outside of Linux
> desktop environments.
> 
> Background:
> -----------
> Typically, Linux desktop environments set the DBUS_SESSION_BUS_ADDRESS
> environment variable. This variable allows the dbus client library to
> directly connect to the existing bus, which is started by the desktop
> environment or systemd.
> When this variable is missing, the dbus client library will fallback
> to auto-launch mode [1], which causes 4 nested fork() + exec() calls.
> Doing this has two problems: (i) slows down startup; (ii) can hang
> the browser if the fork() happens while another thread is in a malloc()
> (Chrome's tcmalloc has no at-fork handlers).
> This situation (no env variable) is very common in test scenarios
> (browsertests, chromedriver, etc).
> 
> Change introduced by this CL:
> -----------------------------
> This CL sets the bus address env variable to "disabled:" if not set.
> This effectively shuts down the dbus auto-launch. If necessary, this
> behavior can be restored by setting, before launching chrome,
> DBUS_SESSION_BUS_ADDRESS="autolaunch:" .
> This workaround will be necessary until libdbus and gspawn are fixed
> to be multi-threading friendly [2,3] and that fix rolls into the
> various distributions.
> The change is introduced in the main embedder rather than in the
> google-chrome wrapper, as several binaries can be affected by this,
> for instance:
> - browser tests (http://crbug.com/693668)
> - chrome --headless
> - webdriver/selenium which seem to directly invoke "chrome"
>    see https://github.com/SeleniumHQ/docker-selenium/issues/87
> 
> [1] https://dbus.freedesktop.org/doc/dbus-launch.1.html
> [2] https://bugs.freedesktop.org/show_bug.cgi?id=100843
> [3] https://bugs.chromium.org/p/chromedriver/issues/detail?id=1699
> 
> BUG=715658,695643,713947
> TEST=strace -ff -o trace chrome; grep dbus-launch trace*
> 
> Review-Url: https://codereview.chromium.org/2861163002
> Cr-Commit-Position: refs/heads/master@{#469987}
> Committed:
https://chromium.googlesource.com/chromium/src/+/8511820ec8280caacbd4f81f3ecd...

TBR=satorux@google.com,thestig@chromium.org,jam@chromium.org,satorux@chromium...
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=715658,695643,713947
==========

to

==========
Revert of Linux: Disable DBus auto-launch (patchset #1 id:1 of
https://codereview.chromium.org/2861163002/ )

Reason for revert:
Speculative revert -- the TSan bots have been reporting a data race when setting
Envvars (in this case, appending to the python path to start a websocket
server). The race appeared immediately after this patch landed, so it may be
legitimate. Reverting this to see if it clears the failures up; if so, we'll
probably just have to serialize the calls to setenv.

Filed crbug.com/719633 for this as well.

Original issue's description:
> Linux: Disable DBus auto-launch
> 
> This is a workaround (ETA ~ 2-3 years) for libdbus not being multi-threading
> friendly and causing random hangs when running chrome outside of Linux
> desktop environments.
> 
> Background:
> -----------
> Typically, Linux desktop environments set the DBUS_SESSION_BUS_ADDRESS
> environment variable. This variable allows the dbus client library to
> directly connect to the existing bus, which is started by the desktop
> environment or systemd.
> When this variable is missing, the dbus client library will fallback
> to auto-launch mode [1], which causes 4 nested fork() + exec() calls.
> Doing this has two problems: (i) slows down startup; (ii) can hang
> the browser if the fork() happens while another thread is in a malloc()
> (Chrome's tcmalloc has no at-fork handlers).
> This situation (no env variable) is very common in test scenarios
> (browsertests, chromedriver, etc).
> 
> Change introduced by this CL:
> -----------------------------
> This CL sets the bus address env variable to "disabled:" if not set.
> This effectively shuts down the dbus auto-launch. If necessary, this
> behavior can be restored by setting, before launching chrome,
> DBUS_SESSION_BUS_ADDRESS="autolaunch:" .
> This workaround will be necessary until libdbus and gspawn are fixed
> to be multi-threading friendly [2,3] and that fix rolls into the
> various distributions.
> The change is introduced in the main embedder rather than in the
> google-chrome wrapper, as several binaries can be affected by this,
> for instance:
> - browser tests (http://crbug.com/693668)
> - chrome --headless
> - webdriver/selenium which seem to directly invoke "chrome"
>    see https://github.com/SeleniumHQ/docker-selenium/issues/87
> 
> [1] https://dbus.freedesktop.org/doc/dbus-launch.1.html
> [2] https://bugs.freedesktop.org/show_bug.cgi?id=100843
> [3] https://bugs.chromium.org/p/chromedriver/issues/detail?id=1699
> 
> BUG=715658,695643,713947
> TEST=strace -ff -o trace chrome; grep dbus-launch trace*
> 
> Review-Url: https://codereview.chromium.org/2861163002
> Cr-Commit-Position: refs/heads/master@{#469987}
> Committed:
https://chromium.googlesource.com/chromium/src/+/8511820ec8280caacbd4f81f3ecd...

TBR=satorux@google.com,thestig@chromium.org,jam@chromium.org,satorux@chromium...
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=715658,695643,713947

Review-Url: https://codereview.chromium.org/2869843003
Cr-Commit-Position: refs/heads/master@{#470059}
Committed:
https://chromium.googlesource.com/chromium/src/+/1e78cb7863da28bb3411286cdbcc...
==========

[commit-bot: I haz the power, 2017-05-08 18:41:52]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/1e78cb7863da28bb3411286cdbcc...

[Primiano Tucci (use gerrit), 2017-05-09 10:58:01]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2865283002/ by primiano@chromium.org.

The reason for reverting is: Adding TSan suppression. The race is independent of
this CL, see crbug.com/719633
.