Cleanup and refactor RootScrollerController.

Cleanup and refactor root scroller machinery.

Some cleanup and restructuring in anticipation of a CL to make root scrollers
work across iframes:

-Removed ChildViewportScrollCallback

This was essentially a no-op ViewportScrollCallback that would be used inside
iframe RootScrollerControllers to make everything more consistent. On reflection,
I think this was a bad choice and we'll just have one ViewportScrollCallback that
gets moved between frames. I've removed ChildViewportScrollCallback and folded
RootViewportScrollCallback into ViewportScrollCallback. RootScrollerController's
m_viewportApplyScroll is now NULL for child frames.

- Initialize ViewportScrollCallback in RootScrollerController

This was in FrameView because FrameView previously didn't expose the
RootFrameViewport which is needed in this callback.  FrameView had to expose
that for other reasons so this cleans things up a little and keeps
RootScrollerController more encapsulated.

- Remove isViewportScrollCallback method on Document

RootScrollerController is now exposed so there's no sense in growing Document's
interface footprint.

- Add m_currentViewportApplyScrollHost

This removes the need for effectiveRootScroller to be the element that has the
apply scroll callback and foreshadows changes coming in a CL to split the
RootScrollerController responsibilities across two classes.

BUG=505516
Committed: https://crrev.com/db5e0d5832ca0259869c57090a5bb6eee0292205
Cr-Commit-Position: refs/heads/master@{#414489}

[bokan, 2016-08-24 23:35:03]

Description was changed from

==========
Cleanup and refactor RootScrollerController.

Some cleanup and restructuring in anticipation of a CL to make root scrollers
work across iframes:

-Removed ChildViewportScrollCallback

This was essentially a no-op ViewportScrollCallback that would be used inside
iframe RootScrollerControllers to make everything more consistent. On
reflection,
I think this was a bad choice and we'll just have one ViewportScrollCallback
that
gets moved between frames. I've removed ChildViewportScrollCallback and folded
RootViewportScrollCallback into ViewportScrollCallback.

- Initialize ViewportScrollCallback in RootScrollerController

This was in FrameView because FrameView previously didn't expose the
RootFrameViewport which is needed in this callback.  FrameView had to expose
that for other reasons so this cleans things up a little and keeps
RootScrollerController more encapsulated.

- Split RootScrollerController into top-document and child-document classes

Work on making RootScrollerController work across iframes revealed that there's
two responsibilities that need management. All iframes need a
RootScrollerController to manage the Element currently set as root scroller and
determining which Element should eventually become the effective root scroller.
In addition, we need the RootScrollerController to manage the
ViewportApplyScroll and set it on the appropriate element. Since only one
Element on the whole page needs this callback set, it makes sense that only the
top document should have this responsibility. Experience with classes like
FrameView and EventHandler shows that this may be better served by subclassing
the top level object rather than having isMainFrame() checks intermingled with
the other code.

BUG=505516
==========

to

==========
Cleanup and refactor root scroller machinery.

Some cleanup and restructuring in anticipation of a CL to make root scrollers
work across iframes:

-Removed ChildViewportScrollCallback

This was essentially a no-op ViewportScrollCallback that would be used inside
iframe RootScrollerControllers to make everything more consistent. On
reflection,
I think this was a bad choice and we'll just have one ViewportScrollCallback
that
gets moved between frames. I've removed ChildViewportScrollCallback and folded
RootViewportScrollCallback into ViewportScrollCallback. RootScrollerController's
m_viewportApplyScroll is now NULL for child frames.

- Initialize ViewportScrollCallback in RootScrollerController

This was in FrameView because FrameView previously didn't expose the
RootFrameViewport which is needed in this callback.  FrameView had to expose
that for other reasons so this cleans things up a little and keeps
RootScrollerController more encapsulated.

- Remove isViewportScrollCallback method on Document

RootScrollerController is now exposed so there's no sense in growing Document's
interface footprint.

- Add m_currentViewportApplyScrollHost

This removes the need for effectiveRootScroller to be the element that has the
apply scroll callback and foreshadows changes coming in a CL to split the
RootScrollerController responsibilities across two classes.

BUG=505516
==========

[bokan, 2016-08-24 23:35:03]

bokan@chromium.org changed reviewers:
+ tdresser@chromium.org

[bokan, 2016-08-24 23:35:27]

Tim, some cleanup before I land a patch to make this work for iframes, PTAL

https://codereview.chromium.org/2273163002/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.h
(right):

https://codereview.chromium.org/2273163002/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.h:37: //
The TopControls and OverscrollController are given to the
Aside from comments, this is just a `git mv RootViewportScrollCallback.cpp|h
ViewportScrollcallback.cpp|h`. Nothing else was changed.

[bokan, 2016-08-24 23:36:19]

The CQ bit was checked by bokan@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-08-24 23:37:35]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-25 01:59:20]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-25 01:59:21]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[tdresser, 2016-08-25 14:46:47]

LGTM

https://codereview.chromium.org/2273163002/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.h
(right):

https://codereview.chromium.org/2273163002/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.h:24: //
applyScroll step of ScrollCustomization. This implementation of
This comment is a bit meandering at this point. Maybe shorten it a bit?

is an applyScroll callback ... is a ScrollStateCallback, meaning that it's
applied during the applyScroll step...

[bokan, 2016-08-25 15:07:16]

On 2016/08/25 14:46:47, tdresser wrote:
> LGTM
> 
>
https://codereview.chromium.org/2273163002/diff/40001/third_party/WebKit/Sour...
> File third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.h
> (right):
> 
>
https://codereview.chromium.org/2273163002/diff/40001/third_party/WebKit/Sour...
> third_party/WebKit/Source/core/page/scrolling/ViewportScrollCallback.h:24: //
> applyScroll step of ScrollCustomization. This implementation of
> This comment is a bit meandering at this point. Maybe shorten it a bit?
> 
> is an applyScroll callback ... is a ScrollStateCallback, meaning that it's
> applied during the applyScroll step...

Done, cleaned it up a bit.

[bokan, 2016-08-25 15:07:36]

The CQ bit was checked by bokan@chromium.org

[bokan, 2016-08-25 15:07:36]

The patchset sent to the CQ was uploaded after l-g-t-m from
tdresser@chromium.org
Link to the patchset: https://codereview.chromium.org/2273163002/#ps60001
(title: "Fixed class comment")

[commit-bot: I haz the power, 2016-08-25 15:07:59]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tdresser, 2016-08-25 15:08:09]

Still LGTM.

[commit-bot: I haz the power, 2016-08-25 18:44:20]

Description was changed from

==========
Cleanup and refactor root scroller machinery.

Some cleanup and restructuring in anticipation of a CL to make root scrollers
work across iframes:

-Removed ChildViewportScrollCallback

This was essentially a no-op ViewportScrollCallback that would be used inside
iframe RootScrollerControllers to make everything more consistent. On
reflection,
I think this was a bad choice and we'll just have one ViewportScrollCallback
that
gets moved between frames. I've removed ChildViewportScrollCallback and folded
RootViewportScrollCallback into ViewportScrollCallback. RootScrollerController's
m_viewportApplyScroll is now NULL for child frames.

- Initialize ViewportScrollCallback in RootScrollerController

This was in FrameView because FrameView previously didn't expose the
RootFrameViewport which is needed in this callback.  FrameView had to expose
that for other reasons so this cleans things up a little and keeps
RootScrollerController more encapsulated.

- Remove isViewportScrollCallback method on Document

RootScrollerController is now exposed so there's no sense in growing Document's
interface footprint.

- Add m_currentViewportApplyScrollHost

This removes the need for effectiveRootScroller to be the element that has the
apply scroll callback and foreshadows changes coming in a CL to split the
RootScrollerController responsibilities across two classes.

BUG=505516
==========

to

==========
Cleanup and refactor root scroller machinery.

Some cleanup and restructuring in anticipation of a CL to make root scrollers
work across iframes:

-Removed ChildViewportScrollCallback

This was essentially a no-op ViewportScrollCallback that would be used inside
iframe RootScrollerControllers to make everything more consistent. On
reflection,
I think this was a bad choice and we'll just have one ViewportScrollCallback
that
gets moved between frames. I've removed ChildViewportScrollCallback and folded
RootViewportScrollCallback into ViewportScrollCallback. RootScrollerController's
m_viewportApplyScroll is now NULL for child frames.

- Initialize ViewportScrollCallback in RootScrollerController

This was in FrameView because FrameView previously didn't expose the
RootFrameViewport which is needed in this callback.  FrameView had to expose
that for other reasons so this cleans things up a little and keeps
RootScrollerController more encapsulated.

- Remove isViewportScrollCallback method on Document

RootScrollerController is now exposed so there's no sense in growing Document's
interface footprint.

- Add m_currentViewportApplyScrollHost

This removes the need for effectiveRootScroller to be the element that has the
apply scroll callback and foreshadows changes coming in a CL to split the
RootScrollerController responsibilities across two classes.

BUG=505516
==========

[commit-bot: I haz the power, 2016-08-25 18:44:21]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2016-08-25 18:47:18]

Description was changed from

==========
Cleanup and refactor root scroller machinery.

Some cleanup and restructuring in anticipation of a CL to make root scrollers
work across iframes:

-Removed ChildViewportScrollCallback

This was essentially a no-op ViewportScrollCallback that would be used inside
iframe RootScrollerControllers to make everything more consistent. On
reflection,
I think this was a bad choice and we'll just have one ViewportScrollCallback
that
gets moved between frames. I've removed ChildViewportScrollCallback and folded
RootViewportScrollCallback into ViewportScrollCallback. RootScrollerController's
m_viewportApplyScroll is now NULL for child frames.

- Initialize ViewportScrollCallback in RootScrollerController

This was in FrameView because FrameView previously didn't expose the
RootFrameViewport which is needed in this callback.  FrameView had to expose
that for other reasons so this cleans things up a little and keeps
RootScrollerController more encapsulated.

- Remove isViewportScrollCallback method on Document

RootScrollerController is now exposed so there's no sense in growing Document's
interface footprint.

- Add m_currentViewportApplyScrollHost

This removes the need for effectiveRootScroller to be the element that has the
apply scroll callback and foreshadows changes coming in a CL to split the
RootScrollerController responsibilities across two classes.

BUG=505516
==========

to

==========
Cleanup and refactor root scroller machinery.

Some cleanup and restructuring in anticipation of a CL to make root scrollers
work across iframes:

-Removed ChildViewportScrollCallback

This was essentially a no-op ViewportScrollCallback that would be used inside
iframe RootScrollerControllers to make everything more consistent. On
reflection,
I think this was a bad choice and we'll just have one ViewportScrollCallback
that
gets moved between frames. I've removed ChildViewportScrollCallback and folded
RootViewportScrollCallback into ViewportScrollCallback. RootScrollerController's
m_viewportApplyScroll is now NULL for child frames.

- Initialize ViewportScrollCallback in RootScrollerController

This was in FrameView because FrameView previously didn't expose the
RootFrameViewport which is needed in this callback.  FrameView had to expose
that for other reasons so this cleans things up a little and keeps
RootScrollerController more encapsulated.

- Remove isViewportScrollCallback method on Document

RootScrollerController is now exposed so there's no sense in growing Document's
interface footprint.

- Add m_currentViewportApplyScrollHost

This removes the need for effectiveRootScroller to be the element that has the
apply scroll callback and foreshadows changes coming in a CL to split the
RootScrollerController responsibilities across two classes.

BUG=505516

Committed: https://crrev.com/db5e0d5832ca0259869c57090a5bb6eee0292205
Cr-Commit-Position: refs/heads/master@{#414489}
==========

[commit-bot: I haz the power, 2016-08-25 18:47:19]

Patchset 4 (id:??) landed as
https://crrev.com/db5e0d5832ca0259869c57090a5bb6eee0292205
Cr-Commit-Position: refs/heads/master@{#414489}