[Android] Fix a bug that snackbar does not show when there is no tab on tablet

[Android] Fix a bug that snackbar does not show when there is no tab on tablet

EmptyBackgroundViewWrapper is the Android View that becomes visible when
there is no tabs on Android tablet Chrome. Since this View hides the
CompositorViewHolder, snackbars becomes not be visible in this mode.

This CL makes EmptyBackgroundViewWrapper aware of SnackbarManager, and
let it override the parent of the snackbar temporarily when it shows up.

BUG=614696
Committed: https://crrev.com/90ddbdf1afd30def9bba4944126c68f8cf10dcbc
Cr-Commit-Position: refs/heads/master@{#399327}

[Ian Wen, 2016-06-01 22:10:26]

ianwen@chromium.org changed reviewers:
+ tedchoc@chromium.org

[Ian Wen, 2016-06-01 22:10:28]

PTAL :)

[Ted C, 2016-06-10 17:58:02]

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
File
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java
(left):

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java:122:
adjustViewPosition();
previously we called adjustViewPosition here, was that not needed?

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
File
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java
(right):

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java:232:
mView.getViewTreeObserver().addOnGlobalLayoutListener(mLayoutListener);
do you need to remove the layout listener in override parent?

[Ian Wen, 2016-06-10 18:55:58]

PTAL :)

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
File
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java
(left):

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java:122:
adjustViewPosition();
On 2016/06/10 17:58:01, Ted C wrote:
> previously we called adjustViewPosition here, was that not needed?

It is not needed. This was a new discovery that I found when I was drafting this
CL. Basically it is meaningless to get the visible display frame from a view
that is not attached to view hierarchy yet. adjustViewPosition() is triggered by
global layout listener, and this is where it is actually helpful.

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
File
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java
(right):

https://codereview.chromium.org/2032773002/diff/1/chrome/android/java/src/org...
chrome/android/java/src/org/chromium/chrome/browser/snackbar/SnackbarView.java:232:
mView.getViewTreeObserver().addOnGlobalLayoutListener(mLayoutListener);
On 2016/06/10 17:58:01, Ted C wrote:
> do you need to remove the layout listener in override parent?

Good call.

In practice removing is not needed. However in theory the layout listener should
be removed first before adding again.

getViewTreeObserver() will always return the same object if the view is attached
to the same window. Even if it is not attached when the listeners was added, the
listeners list will be merged if the view becomes attached. Therefore adding the
same listener to the same object multiple times won't cause actual problems.

However what I found above was implementation detail and we shouldn't rely on
it. Done.

[Ted C, 2016-06-10 19:50:43]

lgtm

[Ian Wen, 2016-06-10 20:04:30]

The CQ bit was checked by ianwen@chromium.org

[commit-bot: I haz the power, 2016-06-10 20:05:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2032773002/20001

[commit-bot: I haz the power, 2016-06-11 00:05:20]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-11 00:05:46]

CQ bit was unchecked

[commit-bot: I haz the power, 2016-06-11 00:09:09]

Description was changed from

==========
[Android] Fix a bug that snackbar does not show when there is no tab on tablet

EmptyBackgroundViewWrapper is the Android View that becomes visible when
there is no tabs on Android tablet Chrome. Since this View hides the
CompositorViewHolder, snackbars becomes not be visible in this mode.

This CL makes EmptyBackgroundViewWrapper aware of SnackbarManager, and
let it override the parent of the snackbar temporarily when it shows up.

BUG=614696
==========

to

==========
[Android] Fix a bug that snackbar does not show when there is no tab on tablet

EmptyBackgroundViewWrapper is the Android View that becomes visible when
there is no tabs on Android tablet Chrome. Since this View hides the
CompositorViewHolder, snackbars becomes not be visible in this mode.

This CL makes EmptyBackgroundViewWrapper aware of SnackbarManager, and
let it override the parent of the snackbar temporarily when it shows up.

BUG=614696

Committed: https://crrev.com/90ddbdf1afd30def9bba4944126c68f8cf10dcbc
Cr-Commit-Position: refs/heads/master@{#399327}
==========

[commit-bot: I haz the power, 2016-06-11 00:09:10]

Patchset 2 (id:??) landed as
https://crrev.com/90ddbdf1afd30def9bba4944126c68f8cf10dcbc
Cr-Commit-Position: refs/heads/master@{#399327}