The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595

commit 3e0a460bd23c5c2e25b8bf6b9813f8c78408a595
Author: bmcquade <bmcquade@chromium.org>
Date: Mon May 09 16:29:07 2016

Log an immediate variant of FirstContentfulPaint.

Our page load metrics are currently logged at the time a page is 'closed'.
For example, when a tab is closed, or when a page is navigated away from.
If a page stays open for a long period of time, we may log its metrics long
after the events for those metrics occurred. This may cause issues such as
logging metrics for events that happened on WiFi later, when the user is on
2G, or vice versa. We don't know how much of a problem this is, so to start,
we're adding a single metric to allow us to track the difference between
logging at the end of a page load and logging immediately after the page
event occurred. If the difference is significant, this may motivate us to
migrate other events to more immediate logging.

BUG= 609660 

Review-Url: https://codereview.chromium.org/1953673003
Cr-Commit-Position: refs/heads/master@{#392330}

[modify] https://crrev.com/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
[modify] https://crrev.com/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
[modify] https://crrev.com/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595/components/page_load_metrics/browser/metrics_web_contents_observer.cc
[modify] https://crrev.com/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595/components/page_load_metrics/browser/metrics_web_contents_observer_unittest.cc
[modify] https://crrev.com/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595/components/page_load_metrics/browser/page_load_metrics_observer.h
[modify] https://crrev.com/3e0a460bd23c5c2e25b8bf6b9813f8c78408a595/tools/metrics/histograms/histograms.xml

Your change meets the bar and is auto-approved for M51 (branch: 2704)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4f077f1f256f242007969dc9548f555c37b56185

commit 4f077f1f256f242007969dc9548f555c37b56185
Author: bmcquade <bmcquade@chromium.org>
Date: Tue May 10 19:01:04 2016

Log an immediate variant of FirstContentfulPaint.

Our page load metrics are currently logged at the time a page is 'closed'.
For example, when a tab is closed, or when a page is navigated away from.
If a page stays open for a long period of time, we may log its metrics long
after the events for those metrics occurred. This may cause issues such as
logging metrics for events that happened on WiFi later, when the user is on
2G, or vice versa. We don't know how much of a problem this is, so to start,
we're adding a single metric to allow us to track the difference between
logging at the end of a page load and logging immediately after the page
event occurred. If the difference is significant, this may motivate us to
migrate other events to more immediate logging.

NOTRY=true
NOPRESUBMIT=true
BUG= 609660 

Review-Url: https://codereview.chromium.org/1953673003
Cr-Commit-Position: refs/heads/master@{#392330}
(cherry picked from commit 3e0a460bd23c5c2e25b8bf6b9813f8c78408a595)

Review-Url: https://codereview.chromium.org/1961363003
Cr-Commit-Position: refs/branch-heads/2704@{#480}
Cr-Branched-From: 6e53600def8f60d8c632fadc70d7c1939ccea347-refs/heads/master@{#386251}

[modify] https://crrev.com/4f077f1f256f242007969dc9548f555c37b56185/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
[modify] https://crrev.com/4f077f1f256f242007969dc9548f555c37b56185/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h
[modify] https://crrev.com/4f077f1f256f242007969dc9548f555c37b56185/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer_unittest.cc
[modify] https://crrev.com/4f077f1f256f242007969dc9548f555c37b56185/components/page_load_metrics/browser/metrics_web_contents_observer.cc
[modify] https://crrev.com/4f077f1f256f242007969dc9548f555c37b56185/components/page_load_metrics/browser/metrics_web_contents_observer_unittest.cc
[modify] https://crrev.com/4f077f1f256f242007969dc9548f555c37b56185/components/page_load_metrics/browser/page_load_metrics_observer.h
[modify] https://crrev.com/4f077f1f256f242007969dc9548f555c37b56185/tools/metrics/histograms/histograms.xml