All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=821962

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=824535b9df05deb5ff5dee33dc9cb095b4ce4df00ffa86d90067a85819f2799f


Bot(s) for this bug's original alert(s):

chromium-rel-mac11-air
chromium-rel-mac11-pro
chromium-rel-mac12
chromium-rel-win7-dual
chromium-rel-win7-gpu-intel
chromium-rel-win7-gpu-nvidia
chromium-rel-win7-x64-dual
chromium-rel-win8-dual

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/138094ee440000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/138094ee440000

Add fieldtrial testing config for new media controls by steimel@chromium.org
https://chromium.googlesource.com/chromium/src/+/fdfc5ae4154a67e0539b9d0a77b3c5e2da38f40b

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/1697e0bfa40000

For some (e.g. [1]), the value had dropped previously, and this alert is when it went back to the previous value. For others (e.g. [2]), the metric recovered later. However, some (e.g.  [3]) haven't recovered, so I'll try another bisect.

[1] https://chromeperf.appspot.com/report?sid=5b3d42dad4430b0b8665eaaf9767a1a5c6cc3a2a0687acac5c1d6682a7fed2ae&start_rev=535275&end_rev=545650
[2] https://chromeperf.appspot.com/report?sid=fb51155a4102482c846a1d3afa130704ac0e3fe73a428653b9f68bbef2ef0190&start_rev=542026&end_rev=548803
[3] https://chromeperf.appspot.com/report?sid=c8c021ab8f77b4100b0989cb7ae6c991138e689b31d8185104e96a674dd3adc9&rev=542559

😿 Pinpoint job stopped with an error.
https://pinpoint-dot-chromeperf.appspot.com/job/1697e0bfa40000

All of the runs failed. The most common error (20/20 runs) was:
BuildError: Build failed: BUILD_FAILURE

Looks like the increased memory was caused by new media controls.