[Merge to M56] Fix the Crash in the launcher's start page on Chrome OS.

[Merge to M56] Fix the Crash in the launcher's start page on Chrome OS.

In Chrome OS launcher's start page, we recreate the app tile views
if we need to display different numbers of apps compared with the
previous time (e.g., install a new app or uninstall an existing app).
We need to make sure the number of the displayed apps is properly
updated. Otherwise, it might cause browser crash because of retrieving
a stale pointer in StartPageView::StartPageTilesContainer::GetTileItemView().

This simple CL is a temporary fix that meant to merge back to M56. It
will be reverted later on Tot and a better but more complicated fix
will be landed.

BUG=675150
TBR=xiyuan@chromium.org

Review-Url: https://codereview.chromium.org/2605463003
Cr-Commit-Position: refs/heads/master@{#441275}
(cherry picked from commit 49ff293042830e095777651dc4058772af41fdda)

Review-Url: https://codereview.chromium.org/2618793002 .
Cr-Commit-Position: refs/branch-heads/2924@{#680}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}
Committed: https://chromium.googlesource.com/chromium/src/+/049fb2e3267a44e8b57f1a178924a4077ad8a66f

[xdai1, 2017-01-05 17:57:18]

Description was changed from

==========
[Merge to M56] Fix the Crash in the launcher's start page on Chrome OS.

In Chrome OS launcher's start page, we recreate the app tile views
if we need to display different numbers of apps compared with the
previous time (e.g., install a new app or uninstall an existing app).
We need to make sure the number of the displayed apps is properly
updated. Otherwise, it might cause browser crash because of retrieving
a stale pointer in StartPageView::StartPageTilesContainer::GetTileItemView().

This simple CL is a temporary fix that meant to merge back to M56. It
will be reverted later on Tot and a better but more complicated fix
will be landed.

BUG=675150
TBR=xiyuan@chromium.org

Review-Url: https://codereview.chromium.org/2605463003
Cr-Commit-Position: refs/heads/master@{#441275}
(cherry picked from commit 49ff293042830e095777651dc4058772af41fdda)
==========

to

==========
[Merge to M56] Fix the Crash in the launcher's start page on Chrome OS.

In Chrome OS launcher's start page, we recreate the app tile views
if we need to display different numbers of apps compared with the
previous time (e.g., install a new app or uninstall an existing app).
We need to make sure the number of the displayed apps is properly
updated. Otherwise, it might cause browser crash because of retrieving
a stale pointer in StartPageView::StartPageTilesContainer::GetTileItemView().

This simple CL is a temporary fix that meant to merge back to M56. It
will be reverted later on Tot and a better but more complicated fix
will be landed.

BUG=675150
TBR=xiyuan@chromium.org

Review-Url: https://codereview.chromium.org/2605463003
Cr-Commit-Position: refs/heads/master@{#441275}
(cherry picked from commit 49ff293042830e095777651dc4058772af41fdda)

Review-Url: https://codereview.chromium.org/2618793002 .
Cr-Commit-Position: refs/branch-heads/2924@{#680}
Cr-Branched-From:
3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}
Committed:
https://chromium.googlesource.com/chromium/src/+/049fb2e3267a44e8b57f1a178924...
==========

[xdai1, 2017-01-05 17:57:19]

Committed patchset #1 (id:1) manually as
049fb2e3267a44e8b57f1a178924a4077ad8a66f (presubmit successful).