This is what the failure looks like:

[ RUN      ] CrSettingsPrivacyPageTest.PrivacyPage
[33133:47887:0826/050953:WARNING:mac_util.mm(255)] Failed to set backup exclusion for file '/private/var/folders/9x/6c6sv3cj4j53wzpzthbp4ksm0000gm/T/.org.chromium.Chromium.ZaqQs1/dKnLF4a/Default/History': Error Domain=NSOSStatusErrorDomain Code=-50 "The operation couldn?t be completed. (OSStatus error -50.)" (paramErr: error in user parameter list) (-50)
[33133:47887:0826/050953:WARNING:mac_util.mm(255)] Failed to set backup exclusion for file '/private/var/folders/9x/6c6sv3cj4j53wzpzthbp4ksm0000gm/T/.org.chromium.Chromium.ZaqQs1/dKnLF4a/Default/Favicons': Error Domain=NSOSStatusErrorDomain Code=-50 "The operation couldn?t be completed. (OSStatus error -50.)" (paramErr: error in user parameter list) (-50)
[33136:1287:0826/050953:WARNING:vt_video_decode_accelerator_mac.cc(164)] Failed to create VTDecompressionSession: Error Domain=NSOSStatusErrorDomain Code=-8973 "The operation couldn?t be completed. (OSStatus error -8973.)" (codecOpenErr) (-8973)
[33136:1287:0826/050953:WARNING:vt_video_decode_accelerator_mac.cc(199)] Failed to create hardware VideoToolbox session
[33136:1287:0826/050954:ERROR:vt_video_encode_accelerator_mac.cc(540)]  VTCompressionSessionCreate failed: -12908
[33133:1287:0826/050955:WARNING:CONSOLE(1)] "This file is deprecated. Please use `iron-flex-layout/iron-flex-layout-classes.html`, and one of the specific dom-modules instead", source: chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-shadow-flex-layout-extracted.js (1)
[33133:1287:0826/050955:WARNING:CONSOLE(1)] "This file is deprecated. Please use `iron-flex-layout/iron-flex-layout-classes.html`, and one of the specific dom-modules instead", source: chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout-extracted.js (1)
[33133:1287:0826/050955:INFO:CONSOLE(1206)] "Running TestCase CrSettingsPrivacyPageTest.PrivacyPage", source: test_api.js (1206)
[33133:1287:0826/050955:WARNING:CONSOLE(0)] "/deep/ combinator is deprecated. See https://www.chromestatus.com/features/6750456638341120 for more details.", source:  (0)
[33133:1287:0826/050956:ERROR:CONSOLE(88)] "Uncaught (in promise) InvalidStateError: Failed to execute 'showModal' on 'HTMLDialogElement': The element is not in a Document.", source: chrome://md-settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js (88)
[33133:1287:0826/050956:INFO:CONSOLE(125)] "Page load time: 579 ms", source: polymer_browser_test_base.js (125)
[33133:1287:0826/050956:INFO:CONSOLE(127)] "Test run time: 789 ms", source: polymer_browser_test_base.js (127)
[33133:1287:0826/050956:INFO:CONSOLE(129)] "Total time: 1368 ms", source: polymer_browser_test_base.js (129)
[33133:1287:0826/050956:ERROR:web_ui_browser_test.cc(462)] CONDITION FAILURE: encountered javascript console error(s):
[33133:1287:0826/050956:ERROR:web_ui_browser_test.cc(464)] JS ERROR: '[33133:1287:0826/050956:ERROR:CONSOLE(88)] "Uncaught (in promise) InvalidStateError: Failed to execute 'showModal' on 'HTMLDialogElement': The element is not in a Document.", source: chrome://md-settings/clear_browsing_data_dialog/clear_browsing_data_dialog.js (88)
'
[33133:1287:0826/050956:ERROR:web_ui_browser_test.cc(466)] JS call assumed failed, because JS console error(s) found.
gen/chrome/test/data/webui/settings/cr_settings_browsertest-gen.cc:515: Failure
Value of: RunJavascriptTestF( true, "CrSettingsPrivacyPageTest", "PrivacyPage")
  Actual: false
Expected: true
[33133:1287:0826/050956:WARNING:url_request_context_getter.cc(43)] URLRequestContextGetter leaking due to no owning thread.
[  FAILED  ] CrSettingsPrivacyPageTest.PrivacyPage, where TypeParam =  and GetParam() =  (2550 ms)

Oldest occurrence for which I have a log file: revision 1683569
Failures happened before, though.

Disabling the test as per sheriff guidlines.

Most tests failed on macs recently. The logs for linux are gone.

try run at 2016-08-31 02:05:47 UTC	patchset	mac_chromium_rel_ng	
try run at 2016-08-30 21:35:06 UTC	patchset	mac_chromium_rel_ng	(reported in 642574)
try run at 2016-08-30 18:11:28 UTC	patchset	mac_chromium_rel_ng	(reported in 642574)
try run at 2016-08-30 12:52:58 UTC	patchset	mac_chromium_rel_ng	(reported in 642574)
try run at 2016-08-29 01:43:02 UTC	patchset	mac_chromium_rel_ng	
try run at 2016-08-26 12:29:10 UTC	patchset	mac_chromium_rel_ng	
 
try run at 2016-08-22 23:05:47 UTC	patchset	mac_chromium_rel_ng	
 
try run at 2016-08-17 17:54:18 UTC	patchset	mac_chromium_rel_ng	
try run at 2016-08-17 00:53:43 UTC	patchset	mac_chromium_rel_ng	
 
try run at 2016-07-29 01:33:25 UTC	patchset	linux_chromium_rel_ng	
try run at 2016-07-29 01:31:14 UTC	patchset	mac_chromium_rel_ng

Suspected culprit: https://chromium.googlesource.com/chromium/src/+/0501e1b4e707a2d7f4a0525f2f9b0b1ba2dac644

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/85a8d40a0c3182554e8915c1d088019210768fb9

commit 85a8d40a0c3182554e8915c1d088019210768fb9
Author: battre <battre@chromium.org>
Date: Wed Aug 31 09:45:33 2016

Disabled flaky CrSettingsPrivacyPageTest.PrivacyPage test

TBR=dpapad@chromium.org
BUG= 642574 , 625332 

Review-Url: https://codereview.chromium.org/2298113002
Cr-Commit-Position: refs/heads/master@{#415596}

[modify] https://crrev.com/85a8d40a0c3182554e8915c1d088019210768fb9/chrome/test/data/webui/settings/cr_settings_browsertest.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5e840a17185f5ee1fd26750fefff0770dd510a64

commit 5e840a17185f5ee1fd26750fefff0770dd510a64
Author: dpapad <dpapad@chromium.org>
Date: Thu Sep 15 20:24:45 2016

MD Settings: Deflake attempt for CrSettingsPrivacyPageTest.PrivacyPage.

In one of the test cases, showModal() was called after the dialog had already
been removed from the DOM from tearDown().

BUG= 642574 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2341493003
Cr-Commit-Position: refs/heads/master@{#418953}

[modify] https://crrev.com/5e840a17185f5ee1fd26750fefff0770dd510a64/chrome/test/data/webui/settings/about_page_tests.js
[modify] https://crrev.com/5e840a17185f5ee1fd26750fefff0770dd510a64/chrome/test/data/webui/settings/certificate_manager_page_test.js
[modify] https://crrev.com/5e840a17185f5ee1fd26750fefff0770dd510a64/chrome/test/data/webui/settings/cr_settings_browsertest.js
[modify] https://crrev.com/5e840a17185f5ee1fd26750fefff0770dd510a64/chrome/test/data/webui/settings/privacy_page_test.js
[add] https://crrev.com/5e840a17185f5ee1fd26750fefff0770dd510a64/chrome/test/data/webui/settings/test_util.js

Closing for now. Will re-open if flakiness continues.

"CrSettingsPrivacyPageTest.PrivacyPage" test failing on mac beta for official.desktop.continuous. reopening the issue.

Link to the builder:
-------------------
https://uberchromegw.corp.google.com/i/official.desktop.continuous/builders/mac%20beta/builds/4965

Link to Log Path:
------------------
https://uberchromegw.corp.google.com/i/official.desktop.continuous/builders/mac%20beta/builds/4965/steps/browser_tests/logs/CrSettingsPrivacyPageTest.PrivacyPage

Error Log:
-----------
Error: Uncaught TypeError: browserProxy.getMetricsReporting is not a function (chrome://md-settings/privacy_page/privacy_page.js:47)
    at Context.<anonymous> (privacy_page_test.js:98:25)
", source: mocha_adapter.js (48)
'
[52587:1287:1017/095903:ERROR:web_ui_browser_test.cc(475)] JS ERROR: '[52587:1287:1017/095903:ERROR:CONSOLE(47)] "Uncaught TypeError: browserProxy.getMetricsReporting is not a function", source: chrome://md-settings/privacy_page/privacy_page.js (47)
'
[52587:1287:1017/095903:ERROR:web_ui_browser_test.cc(475)] JS ERROR: '[52587:1287:1017/095903:ERROR:CONSOLE(48)] "Mocha test failed: PrivacyPage showClearBrowsingDataDialog
AssertionError: expected false to be true
    at Function.assert.isTrue (chai.js:2423:31)
    at assertTrue (test_api.js:851:17)
    at Context.<anonymous> (privacy_page_test.js:108:9)
", source: mocha_adapter.js (48)
'
[52587:1287:1017/095903:ERROR:web_ui_browser_test.cc(475)] JS ERROR: '[52587:1287:1017/095903:ERROR:CONSOLE(48)] "Mocha test failed: PrivacyPage "after each" hook
Error: Script error. (:0)
    at Context.<anonymous> (privacy_page_test.js:102:34)
", source: mocha_adapter.js (48)
'
[52587:1287:1017/095903:ERROR:web_ui_browser_test.cc(477)] JS call assumed failed, because JS console error(s) found.
gen/chrome/test/data/webui/settings/cr_settings_browsertest-gen.cc:515: Failure
Value of: RunJavascriptTestF( true, "CrSettingsPrivacyPageTest", "PrivacyPage")
  Actual: false
Expected: true
[52587:1287:1017/095903:ERROR:CONSOLE(31)] "Uncaught Error: Assertion failed", source: chrome://resources/js/util.js (31)
[  FAILED  ] CrSettingsPrivacyPageTest.PrivacyPage, where TypeParam =  and GetParam() =  (1284 ms)

dpapad@, could you please take a look?