The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6a361fd629fd216c5cb0a1108228a1d10585a136

commit 6a361fd629fd216c5cb0a1108228a1d10585a136
Author: philipj <philipj@opera.com>
Date: Thu Apr 21 08:39:00 2016

Measure usage of generated documents (image/media/plugin/etc)

As discussed on blink-dev:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/u79ubJvsTbI/c_kSGKrEAgAJ

This *InFrame counters are intended as an estimate of cases where a
script in the containing document could look at the generated DOM.

BUG= 597380 
R=esprehn@chromium.org,pdr@chromium.org
TBR=isherman@chromium.org

Review URL: https://codereview.chromium.org/1866343002

Cr-Commit-Position: refs/heads/master@{#388723}

[add] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/LayoutTests/fast/images/image-use-counters.html
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/Source/core/frame/UseCounter.h
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/Source/core/html/HTMLViewSourceDocument.cpp
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/Source/core/html/ImageDocument.cpp
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/Source/core/html/MediaDocument.cpp
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/Source/core/html/PluginDocument.cpp
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/Source/core/html/TextDocument.cpp
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/third_party/WebKit/Source/core/loader/SinkDocument.cpp
[modify] https://crrev.com/6a361fd629fd216c5cb0a1108228a1d10585a136/tools/metrics/histograms/histograms.xml

Woohoo