Reland of [NTP Snippets] Refresh the displayed snippets less frequently

[NTP Snippets] Refresh the displayed snippets less frequently

Relanding the change that was reverted in
https://codereview.chromium.org/1897313002

Original issue's description:
> The fetch frequence of the snippet service does not change, but the
> snippets are now refreshed less frequently on the UI. They are pulled
> when the NTP is opened, or when the user switches back to it from
> another tab or another app.
>
> Additionally, we also change the way the list is updated, adding only
> new entries instead of clearing the old list and replacing it with
> the new one.

BUG=601757, 604763
TBR=bauerb@chromium.org

Committed: https://crrev.com/cb0b829783d26fe083f951a58c2395bef0f06840
Cr-Commit-Position: refs/heads/master@{#388235}

[dgn, 2016-04-19 16:37:26]

Created Reland of [NTP Snippets] Refresh the displayed snippets less frequently

[dgn, 2016-04-19 16:40:41]

Description was changed from

==========
Reland of [NTP Snippets] Refresh the displayed snippets less frequently
(patchset #1 id:1 of https://codereview.chromium.org/1897313002/ )

Reason for revert:
Fixing

Original issue's description:
> Revert of [NTP Snippets] Refresh the displayed snippets less frequently
(patchset #7 id:120001 of https://codereview.chromium.org/1888913002/ )
> 
> Reason for revert:
> testSnippetLoading is failing. Opened new bug: crbug.com/604763
> 
> Original issue's description:
> > [NTP Snippets] Refresh the displayed snippets less frequently
> > 
> > The fetch frequence of the snippet service does not change, but the
> > snippets are now refreshed less frequently on the UI. They are pulled
> > when the NTP is opened, or when the user switches back to it from
> > another tab or another app.
> > 
> > Additionally, we also change the way the list is updated, adding only
> > new entries instead of clearing the old list and replacing it with
> > the new one.
> > 
> > BUG=601757
> > 
> > Committed: https://crrev.com/104124354787e845e02db283185d499232518dd6
> > Cr-Commit-Position: refs/heads/master@{#388195}
> 
> TBR=treib@chromium.org,bauerb@chromium.org,dgn@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=601757

TBR=treib@chromium.org,bauerb@chromium.org,cmumford@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=601757
==========

to

==========
[NTP Snippets] Refresh the displayed snippets less frequently

Relanding the change that was reverted in
https://codereview.chromium.org/1897313002

Original issue's description:
> The fetch frequence of the snippet service does not change, but the
> snippets are now refreshed less frequently on the UI. They are pulled
> when the NTP is opened, or when the user switches back to it from
> another tab or another app.
> 
> Additionally, we also change the way the list is updated, adding only
> new entries instead of clearing the old list and replacing it with
> the new one.

BUG=601757,604763
==========

[dgn, 2016-04-19 17:03:24]

Description was changed from

==========
[NTP Snippets] Refresh the displayed snippets less frequently

Relanding the change that was reverted in
https://codereview.chromium.org/1897313002

Original issue's description:
> The fetch frequence of the snippet service does not change, but the
> snippets are now refreshed less frequently on the UI. They are pulled
> when the NTP is opened, or when the user switches back to it from
> another tab or another app.
> 
> Additionally, we also change the way the list is updated, adding only
> new entries instead of clearing the old list and replacing it with
> the new one.

BUG=601757,604763
==========

to

==========
[NTP Snippets] Refresh the displayed snippets less frequently

Relanding the change that was reverted in
https://codereview.chromium.org/1897313002

Original issue's description:
> The fetch frequence of the snippet service does not change, but the
> snippets are now refreshed less frequently on the UI. They are pulled
> when the NTP is opened, or when the user switches back to it from
> another tab or another app.
> 
> Additionally, we also change the way the list is updated, adding only
> new entries instead of clearing the old list and replacing it with
> the new one.

BUG=601757,604763
TBR=bauerb@chromium.org
==========

[dgn, 2016-04-19 17:03:29]

The CQ bit was checked by dgn@chromium.org

[commit-bot: I haz the power, 2016-04-19 17:03:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1898213002/190001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1898213002/190001

[commit-bot: I haz the power, 2016-04-19 17:35:14]

Committed patchset #2 (id:190001)

[Bernhard Bauer, 2016-04-20 08:16:00]

lgtm

[commit-bot: I haz the power, 2016-04-22 19:13:25]

Description was changed from

==========
[NTP Snippets] Refresh the displayed snippets less frequently

Relanding the change that was reverted in
https://codereview.chromium.org/1897313002

Original issue's description:
> The fetch frequence of the snippet service does not change, but the
> snippets are now refreshed less frequently on the UI. They are pulled
> when the NTP is opened, or when the user switches back to it from
> another tab or another app.
> 
> Additionally, we also change the way the list is updated, adding only
> new entries instead of clearing the old list and replacing it with
> the new one.

BUG=601757,604763
TBR=bauerb@chromium.org
==========

to

==========
[NTP Snippets] Refresh the displayed snippets less frequently

Relanding the change that was reverted in
https://codereview.chromium.org/1897313002

Original issue's description:
> The fetch frequence of the snippet service does not change, but the
> snippets are now refreshed less frequently on the UI. They are pulled
> when the NTP is opened, or when the user switches back to it from
> another tab or another app.
>
> Additionally, we also change the way the list is updated, adding only
> new entries instead of clearing the old list and replacing it with
> the new one.

BUG=601757,604763
TBR=bauerb@chromium.org

Committed: https://crrev.com/cb0b829783d26fe083f951a58c2395bef0f06840
Cr-Commit-Position: refs/heads/master@{#388235}
==========

[commit-bot: I haz the power, 2016-04-22 19:13:25]

Patchset 2 (id:??) landed as
https://crrev.com/cb0b829783d26fe083f951a58c2395bef0f06840
Cr-Commit-Position: refs/heads/master@{#388235}