Let's get this to M60. The change is small enough.

Your change meets the bar and is auto-approved for M60. Please go ahead and merge the CL to branch 3112 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), josafat@(ChromeOS), bustamante@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Leaving this here because the bot did not propagate the initial commit:

commit ba9f2bb42a6f241076156541a84e8767e08cf66c
Author: Becca Hughes <beccahughes@chromium.org>
Date:   Tue Jun 6 10:00:04 2017 +0100

    Record Rappor metrics for Cast overlay useage
    
    Record the origin of the websites on which the overlay is used.
    
    BUG= 728632 
    R=mlamouri@chromium.org, mpearson@chromium.org
    
    Change-Id: I276fc7ca6b00ab6cd538326a36d8143f1947f3ad
    Reviewed-on: https://chromium-review.googlesource.com/521166
    Reviewed-by: Steven Holte <holte@chromium.org>
    Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
    Reviewed-by: Anton Vayvod <avayvod@chromium.org>
    Commit-Queue: Becca Hughes <beccahughes@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#477340}

The merge is landing.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3df58d9034574daf6cb13718747d185608425be3

commit 3df58d9034574daf6cb13718747d185608425be3
Author: Mounir Lamouri <mlamouri@chromium.org>
Date: Fri Jun 09 14:33:07 2017

Record Rappor metrics for Cast overlay useage

Record the origin of the websites on which the overlay is used.

BUG= 728632 
R=mlamouri@chromium.org, mpearson@chromium.org
TBR=beccahughes@chromium.org

(cherry picked from commit ba9f2bb42a6f241076156541a84e8767e08cf66c)

Change-Id: I276fc7ca6b00ab6cd538326a36d8143f1947f3ad
Reviewed-on: https://chromium-review.googlesource.com/521166
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Anton Vayvod <avayvod@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#477340}
Reviewed-on: https://chromium-review.googlesource.com/529107
Cr-Commit-Position: refs/branch-heads/3112@{#279}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
[modify] https://crrev.com/3df58d9034574daf6cb13718747d185608425be3/third_party/WebKit/Source/modules/media_controls/elements/MediaControlCastButtonElement.cpp
[modify] https://crrev.com/3df58d9034574daf6cb13718747d185608425be3/tools/metrics/rappor/rappor.xml