to repro, run the MojoDOMStorageBrowserTest in dom_storage_browsertest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ad48a137fd13bf0966c58f17b667f3828dcd89ed

commit ad48a137fd13bf0966c58f17b667f3828dcd89ed
Author: rockot <rockot@chromium.org>
Date: Mon May 09 18:36:03 2016

Disable tracing in user service

Two problems:

 1. The tracing client library makes some now-invalid
    assumptions about its environment
 2. We don't have a tracing shell client setup properly
    for chrome or browser tests.

The second problem in particular is causing bad behavior
on OS X if anyone tries connecting to mojo:tracing.

This CL removes tracing usage from UserShellClient for
now.

BUG= 609632 
R=erg@chromium.org

Review-Url: https://codereview.chromium.org/1963753002
Cr-Commit-Position: refs/heads/master@{#392378}

[modify] https://crrev.com/ad48a137fd13bf0966c58f17b667f3828dcd89ed/services/user/user_shell_client.cc
[modify] https://crrev.com/ad48a137fd13bf0966c58f17b667f3828dcd89ed/services/user/user_shell_client.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6936a1c58d788c0f6ff847a139c0ff3918aa65b4

commit 6936a1c58d788c0f6ff847a139c0ff3918aa65b4
Author: michaeln <michaeln@chromium.org>
Date: Mon May 09 19:25:53 2016

Enable the MojoDOMSTorageBrowserTests on most platforms now that crbug/608121 is fixed. Still disabled on osx until 609632 is figured out.

BUG= 586194 , 609632 , 608121 
TBR=jam

Review-Url: https://codereview.chromium.org/1947213002
Cr-Commit-Position: refs/heads/master@{#392393}

[modify] https://crrev.com/6936a1c58d788c0f6ff847a139c0ff3918aa65b4/content/browser/dom_storage/dom_storage_browsertest.cc
[modify] https://crrev.com/6936a1c58d788c0f6ff847a139c0ff3918aa65b4/content/public/app/mojo/content_browser_manifest.json
[modify] https://crrev.com/6936a1c58d788c0f6ff847a139c0ff3918aa65b4/services/shell/shell.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7cb36bc89c4e48d81396a5e797362a91ffdb1ff9

commit 7cb36bc89c4e48d81396a5e797362a91ffdb1ff9
Author: michaeln <michaeln@chromium.org>
Date: Tue May 10 19:30:51 2016

Enable MojoDOMStorageBrowserTest on OSX too.

BUG= 609632 

Review-Url: https://codereview.chromium.org/1962713003
Cr-Commit-Position: refs/heads/master@{#392683}

[modify] https://crrev.com/7cb36bc89c4e48d81396a5e797362a91ffdb1ff9/content/browser/dom_storage/dom_storage_browsertest.cc