Changing the title to reflect that we could add more general metrics.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/37853844afa06038c94e5ce6d8b75d1db9faf2a6

commit 37853844afa06038c94e5ce6d8b75d1db9faf2a6
Author: csharrison <csharrison@chromium.org>
Date: Tue May 17 21:25:09 2016

Log histograms for preloads and preload misses

This patch logs preloads and preload misses when the ResourceFetcher
clears its preloads. It also removes the debug preload macros which seem
unused, given that their implementation doesn't even compile.

BUG= 603274 

Review-Url: https://codereview.chromium.org/1973073005
Cr-Commit-Position: refs/heads/master@{#394234}

[modify] https://crrev.com/37853844afa06038c94e5ce6d8b75d1db9faf2a6/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
[modify] https://crrev.com/37853844afa06038c94e5ce6d8b75d1db9faf2a6/third_party/WebKit/Source/core/fetch/ResourceFetcher.h
[modify] https://crrev.com/37853844afa06038c94e5ce6d8b75d1db9faf2a6/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bfd430ec1aa83a4a667945453913bc51ab4fc580

commit bfd430ec1aa83a4a667945453913bc51ab4fc580
Author: csharrison <csharrison@chromium.org>
Date: Wed Jun 01 00:50:50 2016

Add UMA to track time between preload discovery and reference.

Reference in this case is whenever the preloaded resource has
a ResourceClient added to it. This yields an upper bound on
the wins of the preload scanner, by tracking the time between
scanner discovery and DOM discovery.

BUG= 603274 

Review-Url: https://codereview.chromium.org/1987013002
Cr-Commit-Position: refs/heads/master@{#396999}

[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/third_party/WebKit/Source/core/fetch/FetchRequest.cpp
[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/third_party/WebKit/Source/core/fetch/FetchRequest.h
[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/third_party/WebKit/Source/core/fetch/Resource.cpp
[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/third_party/WebKit/Source/core/fetch/Resource.h
[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp
[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/third_party/WebKit/Source/core/html/parser/HTMLResourcePreloader.cpp
[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/third_party/WebKit/Source/core/loader/LinkLoader.cpp
[modify] https://crrev.com/bfd430ec1aa83a4a667945453913bc51ab4fc580/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5a6a1cf9771fb99913ff5296e6c9f2b8f2cd17ec

commit 5a6a1cf9771fb99913ff5296e6c9f2b8f2cd17ec
Author: csharrison <csharrison@chromium.org>
Date: Fri Jun 03 04:45:59 2016

Add UMA to track time between preload discovery and first bytes of response

BUG= 603274 

Review-Url: https://codereview.chromium.org/2020323003
Cr-Commit-Position: refs/heads/master@{#397634}

[modify] https://crrev.com/5a6a1cf9771fb99913ff5296e6c9f2b8f2cd17ec/third_party/WebKit/Source/core/fetch/Resource.cpp
[modify] https://crrev.com/5a6a1cf9771fb99913ff5296e6c9f2b8f2cd17ec/tools/metrics/histograms/histograms.xml

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cfb243c66139d26bccc8056f34a006d2588e86d3

commit cfb243c66139d26bccc8056f34a006d2588e86d3
Author: csharrison <csharrison@chromium.org>
Date: Fri Jun 24 05:30:02 2016

Add HTML parser UMA for rewinds and chunk queue statistics.

This patch adds uma for how many tokens we had to rewind the BG parser,
as well as the peak size of the pending chunk queue, in chunk length and
token length. We also log the time it takes to create a chunk/checkpoint,
which can involve lengthy string copies.

This is in preparation for an experiment where the parser's behavior with
the queue will be modified.

BUG= 603274 

Review-Url: https://codereview.chromium.org/2078723002
Cr-Commit-Position: refs/heads/master@{#401819}

[modify] https://crrev.com/cfb243c66139d26bccc8056f34a006d2588e86d3/third_party/WebKit/Source/core/html/parser/BackgroundHTMLParser.cpp
[modify] https://crrev.com/cfb243c66139d26bccc8056f34a006d2588e86d3/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.cpp
[modify] https://crrev.com/cfb243c66139d26bccc8056f34a006d2588e86d3/third_party/WebKit/Source/core/html/parser/ParsedChunkQueue.cpp
[modify] https://crrev.com/cfb243c66139d26bccc8056f34a006d2588e86d3/third_party/WebKit/Source/core/html/parser/ParsedChunkQueue.h
[modify] https://crrev.com/cfb243c66139d26bccc8056f34a006d2588e86d3/tools/metrics/histograms/histograms.xml