The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8

commit dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8
Author: dgn <dgn@chromium.org>
Date: Fri Mar 18 17:27:50 2016

Add a flag to disable to New Tab Page toolbar

It is implemented using the base::Feature API. Use the command line
flag `--disable-features=NTPToolbar` to disable it.

BUG= 595362 

Review URL: https://codereview.chromium.org/1806313002

Cr-Commit-Position: refs/heads/master@{#382004}

[modify] https://crrev.com/dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8/chrome/android/java/src/org/chromium/chrome/browser/ChromeFeatureList.java
[modify] https://crrev.com/dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java
[modify] https://crrev.com/dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
[modify] https://crrev.com/dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8/chrome/browser/android/chrome_feature_list.cc
[modify] https://crrev.com/dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8/chrome/browser/android/chrome_feature_list.h

We want to add some new elements to the NTP, cards that will come up from the bottom of the page. The bottom toolbar is in the way and its features are already accessible from the main Chrome menu, which is available everywhere. So we want to see if removing that toolbar is acceptable and users manage to easily achieve their task by using the menu items.

Existing metrics that we could use:
- MobileMenuAllBookmarks/MobileMenuOpenTabs - Records taps on the items in the menu
- MobileNTPSwitchToBookmarks/MobileNTPSwitchToOpenTabs - Records taps on the items on the NTP

It is also possible to reach the native pages (RecentTabs, Bookmarks on tablet) by other means, but I guess the metrics above are enough for this experiment.

nepper@, WDYT? should we be tracking something else?

We also have the NewTabPage.ActionAndroid histogram, which records when the user opens a bookmark or a recently closed tab. That's probably the best indicator of whether bookmarks and recent tabs usage has been affected.

+1, we'd like to take a look at all entry points that are presented in the
NTP context:

- bookmarks and recently closed access points in the overflow menu
- bookmarks and recently closed buttons on the NTP

I think the combination of what the two of you suggested should provide
that coverage.

dgn, would it make sense to take a quick glimpse at the actual
implementation of these metrics? I'd like to make sure they measure what we
think they measure.

Thanks

Patrick

The metrics should work as advertised. It's hooked on the entry points we care about. The MobileMenuAllBookmarks will also include cases where the Bookmarks page is opened using keyboard shortcuts.

NewTabPage.ActionAndroid is also very relevant, but it looks at actions that are performed on the bookmarks or recent tabs page, as explained in #6. If all goes well, the numbers in the experimental group should not decrease.

I took a look at the current metrics. Users use the menu to get to bookmarks 2.5x more often than the NTP; but for recent tabs the trend is reversed: they use the NTP 2x as often.

MobileMenuAllBookmarks -     27311502
MobileNTPSwitchToBookmarks - 11687531

MobileMenuOpenTabs -          3445186
MobileNTPSwitchToOpenTabs -   7147894

Hopefully recent tabs users are able to find the recent tabs menu item. It's also possible that people click "recent tabs" on the NTP because they actually want to go to History, whereas the menu has an item to go directly to History so there's no need to click "Recent Tabs" in the menu.

> It's also possible that people click "recent tabs" on the NTP because they actually want to go to History

Possible, yes. Looking at NewTabPage.ActionAndroid,

We have:
- Opened a recently closed tab      181,920
- Opened a bookmark	          5,384,983

That hints that people go to recent tabs but don't use often links there. Going to the History would explain it.

Necessary code landed, experiment status will be tracked in issue 596875.

Issue 598244 has been merged into this issue.

Reopening to track landing the experimentation code cleanup

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf

commit e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf
Author: dgn <dgn@chromium.org>
Date: Mon Aug 22 20:27:58 2016

Revert of "Add a flag to disable to New Tab Page toolbar"
(patchset #3 id:40001 of https://codereview.chromium.org/1806313002/ )

Reason for revert:
Terminating the experiment

Original issue's description:
> Add a flag to disable to New Tab Page toolbar
>
> It is implemented using the base::Feature API. Use the command line
> flag `--disable-features=NTPToolbar` to disable it.
>
> BUG= 595362 
>
> Committed: https://crrev.com/dd8b63c8a415bb8e4eaad0c7bfb4dd6ae5792ed8
> Cr-Commit-Position: refs/heads/master@{#382004}

BUG= 595362 

Review-Url: https://codereview.chromium.org/2269703002
Cr-Commit-Position: refs/heads/master@{#413521}

[modify] https://crrev.com/e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf/chrome/android/java/src/org/chromium/chrome/browser/ChromeFeatureList.java
[modify] https://crrev.com/e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java
[modify] https://crrev.com/e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
[modify] https://crrev.com/e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf/chrome/android/javatests/src/org/chromium/chrome/browser/ntp/snippets/ArticleSnippetsTest.java
[modify] https://crrev.com/e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf/chrome/browser/android/chrome_feature_list.cc
[modify] https://crrev.com/e523b741f5eddc65e4b4fdfe5ab287a8f41c6aaf/chrome/browser/android/chrome_feature_list.h