Show ChromeVox caption panel when spoken feedback is enabled.

ash/shelf/shelf_layout_manager.h

Index: ash/shelf/shelf_layout_manager.h
diff --git a/ash/shelf/shelf_layout_manager.h b/ash/shelf/shelf_layout_manager.h
index 8b5d166a1ef5d03843d9b5612ba9635a008af453..f2dcf0fac974d4269abcdd30be716d318c7f4b08 100644
--- a/ash/shelf/shelf_layout_manager.h
+++ b/ash/shelf/shelf_layout_manager.h
@@ -215,6 +215,9 @@ class ASH_EXPORT ShelfLayoutManager
   // Is the shelf's alignment horizontal?
   bool IsHorizontalAlignment() const;
 
+  // Get the work area insets due to the shelf and virtual keyboard.
+  gfx::Insets GetWorkAreaInsets() const;
+
   // Returns a ShelfLayoutManager on the display which has a shelf for
   // given |window|. See RootWindowController::ForShelf for more info.
   static ShelfLayoutManager* ForShelf(aura::Window* window);
@@ -412,6 +415,10 @@ class ASH_EXPORT ShelfLayoutManager
   // keyboard.
   gfx::Rect user_work_area_bounds_;
 
+  // The insets from the sides of the screen taken up by the shelf or virtual
+  // keyboard.
+  gfx::Insets work_area_insets_;

[oshima, 2015/11/05 23:58:50]

Insets is managed in gfx::Display, and you can obtain it through gfx::Screen.
Please use it instead.

[dmazzoni, 2015/11/06 17:28:14]

Currently ShelfLayoutManager updates the insets by calling
Shell::SetDisplayWorkAreaInsets, which updates the insets in the gfx::Display.
That works fine when the Shelf is the only place that wants to contribute to the
insets, but it doesn't work when we possibly want to get insets from different
places.

I refactored the code so that the shelf keeps track of its desired insets, and
the accessibility delegate can be queried for its desired insets, and when
anything changes, the Shell computes the new merged insets and updates the
display.

Querying the insets from gfx::Display here would be backwards.

[oshima, 2015/11/06 18:21:15]

Is there a reason to store this? Looks like you can just union insets when you
set the insets?

[dmazzoni, 2015/11/09 23:02:06]

What if the ChromeVox Panel closes and wants to update the work area? We can't
un-union the insets from the Display to figure out what the shelf insets are.

If we didn't want to keep track of the insets due to the shelf here, I think
what we'd have to do is:

1) Make ShelfLayoutManager responsible for unioning the insets due to the shelf
with the insets due to accessibility - that's fine with me if you prefer, but it
didn't seem as clean to me - shouldn't ShelfLayoutManager be just about the
shelf?

2) When the ChromeVoxPanel closes, the ShelfLayoutManager would have to
recompute its insets by calling CalculateTargetBounds and
UpdateBoundsAndOpacity. It may be fine but glancing through the code I'm a bit
worried about calling that when it happens to be in the middle of a shelf
animation, it looks like it would reset the animation unless I refactored it a
lot.

Maybe there's an easier way I'm not seeing, but if so please explain how a
sequence like this would work:

1. Initially, ChromeVoxPanel is hidden and shelf is hidden
2. Show ChromeVoxPanel
3. Show shelf
4. Hide ChromeVoxPanel - what happens now to recompute the insets?

[oshima, 2015/11/10 01:47:31]

There is already another factor (dock window) that affect the size of the
workspace, and ShelfLayoutMmanager is responsible for computing insets now.
Ideally, we should refactor
and move the responsibility to a separate class, but if we dont, then I prefer
not to split the responsibility.

Re: animation, the same animation will be applied since the shelf's state didn't
change, and it will continue where it stopped because it's using
IMMEDIATELY_ANIMATE_TO_NEW_TARGET.
You can call call ShelfLayoutMananger::LayoutShelf(true /* animate */), in which
you can call AccessibilityDelegate. I'm actually fine if you want to store the
bounds for chromebox panel instead of adding delegate method, if you like.

+
   // The show hide animation duration override or 0 for default.
   int duration_override_in_ms_;