Delete code involving overdraw bottom height.

Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  overdraw_bottom_height was
zero the vast majority of the time, though, so it seems unlikely that any layout
relies on this.

BUG=404315
Committed: https://crrev.com/7dd28324d2477475b898b10c6ffc7d0b62bd92b5
Cr-Commit-Position: refs/heads/master@{#370355}

[aelias_OOO_until_Jul13, 2016-01-14 20:21:21]

Description was changed from

==========
Delete dead code involving overdraw bottom height.

BUG=
==========

to

==========
Delete dead code involving overdraw bottom height.

[WIP, still needs fixes before review]

BUG=
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:01:10]

Description was changed from

==========
Delete dead code involving overdraw bottom height.

[WIP, still needs fixes before review]

BUG=
==========

to

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height
always zero, with some late deletion of code that was formerly downstream.  This
also deletes two pieces of not-strictly-dead code that appear no longer to be
useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:01:29]

Description was changed from

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height
always zero, with some late deletion of code that was formerly downstream.  This
also deletes two pieces of not-strictly-dead code that appear no longer to be
useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=
==========

to

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was formerly downstream.  This
also deletes two pieces of not-strictly-dead code that appear no longer to be
useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:02:14]

Description was changed from

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was formerly downstream.  This
also deletes two pieces of not-strictly-dead code that appear no longer to be
useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=
==========

to

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was formerly downstream.  This
also deletes two pieces of not-strictly-dead code that appear no longer to be
useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:03:17]

Description was changed from

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was formerly downstream.  This
also deletes two pieces of not-strictly-dead code that appear no longer to be
useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was downstream at the time. 
This also deletes two pieces of not-strictly-dead code that appear no longer to
do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:03:17]

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

[aelias_OOO_until_Jul13, 2016-01-15 03:03:37]

Description was changed from

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was downstream at the time. 
This also deletes two pieces of not-strictly-dead code that appear no longer to
do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was downstream at the time.
This also deletes two pieces of related, not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:04:54]

Description was changed from

==========
Delete dead code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of code that was downstream at the time.
This also deletes two pieces of related, not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:05:13]

Description was changed from

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:05:52]

Description was changed from

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Setting of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:06:39]

Description was changed from

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
this was populated with the View information, so strictly speaking this wasn't
always zero.  It was zero the vast majority of the time, though, so it seems
unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so strictly
speaking it wasn't always zero.  It was zero the vast majority of the time,
though, so it seems unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-15 03:07:15]

Hi tedchoc@, PTAL.

[Ted C, 2016-01-15 17:13:35]

tedchoc@chromium.org changed reviewers:
+ changwan@chromium.org, dtrainor@chromium.org

[Ted C, 2016-01-15 17:13:36]

Seems fine to me, but I am not at all familiar with this code anymore.

I would defer to changwan or dtrainor, but this might be in general lost to the
ether of time, in which case I'm happy to approve and see if there is any
fallout.

[David Trainor- moved to gerrit, 2016-01-20 07:35:36]

Re "2)", so in some cases we had a situation where the mVisibleContentViewport
was empty (top == bottom)?

If we've already made overdraw bottom height 0, this change looks like a noop
aside from that.  I'm fine with it though... we just branched so we have some
headroom if anything odd shows up.

lgtm.

[aelias_OOO_until_Jul13, 2016-01-20 07:53:10]

Description was changed from

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so strictly
speaking it wasn't always zero.  It was zero the vast majority of the time,
though, so it seems unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  It was zero the vast majority of
the time, though, so it seems unlikely that any layout relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-20 07:55:02]

On 2016/01/20 at 07:35:36, dtrainor wrote:
> Re "2)", so in some cases we had a situation where the mVisibleContentViewport
was empty (top == bottom)?

No, I don't know of such a scenario.  It sounds you interpreted the word "it" in
my description to mean mCachedVisibleViewport, I meant overdraw_bottom_height
there; I rewrote it for clarity.

[aelias_OOO_until_Jul13, 2016-01-20 07:55:47]

Description was changed from

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  It was zero the vast majority of
the time, though, so it seems unlikely that any layout relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  overdraw_bottom_height was already

zero the vast majority of the time, though, so it seems unlikely that any layout
relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-20 07:56:42]

Description was changed from

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  overdraw_bottom_height was already

zero the vast majority of the time, though, so it seems unlikely that any layout
relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  overdraw_bottom_height was 
zero the vast majority of the time, though, so it seems unlikely that any layout
relies on this.

BUG=404315
==========

[aelias_OOO_until_Jul13, 2016-01-20 07:56:58]

The CQ bit was checked by aelias@chromium.org

[commit-bot: I haz the power, 2016-01-20 07:57:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1584993002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1584993002/40001

[commit-bot: I haz the power, 2016-01-20 09:17:53]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-01-20 09:19:12]

Description was changed from

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height 
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  overdraw_bottom_height was 
zero the vast majority of the time, though, so it seems unlikely that any layout
relies on this.

BUG=404315
==========

to

==========
Delete code involving overdraw bottom height.

This code follows up r291306 making renderer-reported overdraw_bottom_height
always zero, with some late deletion of dead code that was downstream at the
time.  This also deletes two pieces of not-strictly-dead code that appear no
longer to do anything useful:

1) The workaround for http://crbug.com/440469.  I can no longer reproduce on a
Lollipop Nexus 10 with the workaround deleted.

2) Mutation of mCachedVisibleViewport.  When we don't have a visible renderer,
overdraw_bottom_height was populated with the View information, so in
theory the mutation could've done something.  overdraw_bottom_height was
zero the vast majority of the time, though, so it seems unlikely that any layout
relies on this.

BUG=404315

Committed: https://crrev.com/7dd28324d2477475b898b10c6ffc7d0b62bd92b5
Cr-Commit-Position: refs/heads/master@{#370355}
==========

[commit-bot: I haz the power, 2016-01-20 09:19:13]

Patchset 3 (id:??) landed as
https://crrev.com/7dd28324d2477475b898b10c6ffc7d0b62bd92b5
Cr-Commit-Position: refs/heads/master@{#370355}