Chrome Version: 4b523c1060e2bc62bceb42e3d1674635cd48f2e0
OS: macOS 10.13 High Sierra

What steps will reproduce the problem?
(1) Run content_browsertests on 10.13
(2) CaptureScreenshotTest.CaptureScreenshot and CaptureScreenshotTest.CaptureScreenshotJpeg fail

[ RUN      ] CaptureScreenshotTest.CaptureScreenshot
[68734:33815:0725/013435.947426:21218814660443:ERROR:devtools_http_handler.cc(786)] 
DevTools listening on 127.0.0.1:63764
[68734:775:0725/013436.527348:21219394570948:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,4): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527387:21219394606100:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,5): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527397:21219394616191:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,6): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527406:21219394624346:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,7): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527414:21219394632287:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,8): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527422:21219394640404:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,9): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527430:21219394648795:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,10): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527438:21219394656865:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,11): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527446:21219394664949:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,12): expected 4279383126 actual 4279447116
[68734:775:0725/013436.527454:21219394672953:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,13): expected 4279383126 actual 4279447116
[68734:775:0725/013436.546288:21219413509427:ERROR:devtools_protocol_browsertest.cc(602)] Number of pixel with an error: 468864
[68734:775:0725/013436.546315:21219413534170:ERROR:devtools_protocol_browsertest.cc(603)] Error Bounding Box : 4,4 792x592
../../content/browser/devtools/protocol/devtools_protocol_browsertest.cc:646: Failure
Value of: MatchesBitmap(expected_bitmap, *result_bitmap, matching_mask, error_limit)
  Actual: false
Expected: true
[  FAILED  ] CaptureScreenshotTest.CaptureScreenshot, where TypeParam =  and GetParam() =  (661 ms)

[ RUN      ] CaptureScreenshotTest.CaptureScreenshotJpeg
[68738:33815:0725/013436.745273:21219612505066:ERROR:devtools_http_handler.cc(786)] 
DevTools listening on 127.0.0.1:63765
[68738:775:0725/013437.325174:21220192397704:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,4): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325215:21220192434216:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,5): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325225:21220192443491:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,6): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325233:21220192451785:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,7): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325241:21220192459713:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,8): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325249:21220192467756:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,9): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325257:21220192476063:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,10): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325265:21220192483994:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,11): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325273:21220192491850:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,12): expected 4279383126 actual 4279447116
[68738:775:0725/013437.325281:21220192499686:ERROR:devtools_protocol_browsertest.cc(592)] Pixel (4,13): expected 4279383126 actual 4279447116
[68738:775:0725/013437.346191:21220213413908:ERROR:devtools_protocol_browsertest.cc(602)] Number of pixel with an error: 468864
[68738:775:0725/013437.346220:21220213438739:ERROR:devtools_protocol_browsertest.cc(603)] Error Bounding Box : 4,4 792x592
../../content/browser/devtools/protocol/devtools_protocol_browsertest.cc:646: Failure
Value of: MatchesBitmap(expected_bitmap, *result_bitmap, matching_mask, error_limit)
  Actual: false
Expected: true
[  FAILED  ] CaptureScreenshotTest.CaptureScreenshotJpeg, where TypeParam =  and GetParam() =  (662 ms)


What is the expected result?
Test passes

What happens instead?
Test fails

Please use labels and text to provide additional information.

Job: https://luci-milo.appspot.com/buildbot/chromium.fyi/Chromium%20Mac%2010.13/2
Logs: https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Fchromium.fyi%2FChromium_Mac_10.13%2F2%2F%2B%2Frecipes%2Fsteps%2Fcontent_browsertests%2F0%2Fstdout


For graphics-related bugs, please copy/paste the contents of the about:gpu
page at the end of this report.