Add UMA for studying download cancellation reasons

Add UMA for studying download cancellation reasons

We found high cancellation rate with new download experiment.
This CL is to study why user cancels the download

BUG=618864
Committed: https://crrev.com/8211e681b8a98df75bf56e05d30d4179033cee3e
Cr-Commit-Position: refs/heads/master@{#399521}

[qinmin, 2016-06-09 23:25:33]

qinmin@chromium.org changed reviewers:
+ isherman@chromium.org, tedchoc@chromium.org

[qinmin, 2016-06-09 23:25:33]

PTAL

[Ilya Sherman, 2016-06-10 21:20:43]

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
File content/public/browser/android/download_controller_android.h (right):

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
content/public/browser/android/download_controller_android.h:28: enum
DownloadCancelReason {
nit: Please document that this enum is used to back an UMA histogram, and
therefore should be treated as append-only.

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
content/public/browser/android/download_controller_android.h:33:
kCancelReasonMax
nit: Please use SHOUTY_CASE for enum names, per
https://www.chromium.org/developers/coding-style#TOC-Naming

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
content/public/browser/android/download_controller_android.h:33:
kCancelReasonMax
nit: Also, please either define this as an enum class, or use a common prefix
for each constant name, like CANCEL_REASON_.

https://codereview.chromium.org/2058593002/diff/1/tools/metrics/histograms/hi...
File tools/metrics/histograms/histograms.xml (right):

https://codereview.chromium.org/2058593002/diff/1/tools/metrics/histograms/hi...
tools/metrics/histograms/histograms.xml:23431: +  <summary>Android: Records the
reason that a download is canceled.</summary>
I'd recommend also including in this histogram a bucket for "The download wasn't
cancelled".  That way, you can see how frequently downloads get canceled vs. not
being canceled, as well as the breakdown of cancelation reasons.

[qinmin, 2016-06-11 00:13:00]

Added enum for downloads that are not cancelled

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
File content/public/browser/android/download_controller_android.h (right):

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
content/public/browser/android/download_controller_android.h:28: enum
DownloadCancelReason {
On 2016/06/10 21:20:43, Ilya Sherman wrote:
> nit: Please document that this enum is used to back an UMA histogram, and
> therefore should be treated as append-only.

Done.

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
content/public/browser/android/download_controller_android.h:33:
kCancelReasonMax
On 2016/06/10 21:20:43, Ilya Sherman wrote:
> nit: Also, please either define this as an enum class, or use a common prefix
> for each constant name, like CANCEL_REASON_.

Done.

https://codereview.chromium.org/2058593002/diff/1/content/public/browser/andr...
content/public/browser/android/download_controller_android.h:33:
kCancelReasonMax
On 2016/06/10 21:20:43, Ilya Sherman wrote:
> nit: Please use SHOUTY_CASE for enum names, per
> https://www.chromium.org/developers/coding-style#TOC-Naming

Done.

[Ilya Sherman, 2016-06-11 00:23:59]

LGTM, thanks.

[Ted C, 2016-06-13 17:52:55]

lgtm

[qinmin, 2016-06-13 19:00:25]

The CQ bit was checked by qinmin@chromium.org

[commit-bot: I haz the power, 2016-06-13 19:00:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2058593002/20001

[commit-bot: I haz the power, 2016-06-13 20:16:43]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-13 20:16:45]

CQ bit was unchecked

[commit-bot: I haz the power, 2016-06-13 20:19:47]

Description was changed from

==========
Add UMA for studying download cancellation reasons

We found high cancellation rate with new download experiment.
This CL is to study why user cancels the download

BUG=618864
==========

to

==========
Add UMA for studying download cancellation reasons

We found high cancellation rate with new download experiment.
This CL is to study why user cancels the download

BUG=618864

Committed: https://crrev.com/8211e681b8a98df75bf56e05d30d4179033cee3e
Cr-Commit-Position: refs/heads/master@{#399521}
==========

[commit-bot: I haz the power, 2016-06-13 20:19:49]

Patchset 2 (id:??) landed as
https://crrev.com/8211e681b8a98df75bf56e05d30d4179033cee3e
Cr-Commit-Position: refs/heads/master@{#399521}