Simplify access to LegacyRenderWidgetHostHWND.

Simplify access to LegacyRenderWidgetHostHWND.

Instead of giving BrowserAccessibilityManagerWin a pointer
to a LegacyRenderWidgetHostHWND, which has been a source of
problems due to complicated lifecycles, just have BAMW
request the parent HWND and parent IAccessible from its
delegate whenever needed, with the understanding that these
may be NULL sometimes.

Note: this change fixes a DrMemory UAF detected in the
patch that migrated accessibility from RVH to RFH
(codereview.chromium.org/273423004), and also fixes
a potential concern in another fix to
LegacyRenderWidgetHostHWND (codereview.chromium.org/387353004).

BUG=368298, 393665
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285818

[jam, 2014-07-24 01:15:48]

rubberstamp lgtm for files outside of accessibility

https://codereview.chromium.org/415633002/diff/1/content/browser/renderer_hos...
File content/browser/renderer_host/render_widget_host_view_aura.cc (right):

https://codereview.chromium.org/415633002/diff/1/content/browser/renderer_hos...
content/browser/renderer_host/render_widget_host_view_aura.cc:1204:
RenderWidgetHostViewAura::AccessibilityGetAcceleratedWidget() {
nit: here and below, the style guide says no indentation

https://codereview.chromium.org/415633002/diff/1/content/browser/renderer_hos...
content/browser/renderer_host/render_widget_host_view_aura.cc:1206: if
(legacy_render_widget_host_HWND_)
i realize this existed before, but this shouldn't use upper case for any of the
variable's name

[dmazzoni, 2014-07-24 21:48:22]

+aboxhall to review the accessibility code

[aboxhall, 2014-07-25 16:14:48]

LGTM for c/b/accessibility/*

[dmazzoni, 2014-07-26 21:13:48]

https://codereview.chromium.org/415633002/diff/1/content/browser/renderer_hos...
File content/browser/renderer_host/render_widget_host_view_aura.cc (right):

https://codereview.chromium.org/415633002/diff/1/content/browser/renderer_hos...
content/browser/renderer_host/render_widget_host_view_aura.cc:1204:
RenderWidgetHostViewAura::AccessibilityGetAcceleratedWidget() {
On 2014/07/24 01:15:47, jam wrote:
> nit: here and below, the style guide says no indentation 

Done.

https://codereview.chromium.org/415633002/diff/1/content/browser/renderer_hos...
content/browser/renderer_host/render_widget_host_view_aura.cc:1206: if
(legacy_render_widget_host_HWND_)
On 2014/07/24 01:15:47, jam wrote:
> i realize this existed before, but this shouldn't use upper case for any of
the
> variable's name

I'll clean this up shortly, thanks.

[dmazzoni, 2014-07-26 21:13:53]

The CQ bit was checked by dmazzoni@chromium.org

[commit-bot: I haz the power, 2014-07-26 21:14:04]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dmazzoni@chromium.org/415633002/10001

[commit-bot: I haz the power, 2014-07-26 23:34:45]

Change committed as 285818