Fix a crash which occurs while dragging tabs back to the window where they originated from.

Fix a crash which occurs while dragging tabs back to the window where they originated from.

Reason for the crash is the recent change to the WebView::AttachWebContents function to show the
WebContentsView when the WCV's root window is NULL. This can happen if the tab was detached and
is being reattched in which case the clipping window is removed, etc.

The actual crash occurs in the RWHVA::WasShown function where we dereference a NULL host pointer
due to a NULL root window.

Fix is to show the WCV after the attach has happened in the holder. This works correctly and is required for the Legacy window to show up correctly.
I verified that WC::Show and WC::Hide only get called once and the same is true with RWHVA::WasShown/WasHidden.

I updated the TestWebViewAttachDetachWebContents webview unittest to check for a NULL root window
when WC::WasShown is fired and we test for the same.

BUG=415509
Committed: https://crrev.com/d9b817cc6c0f976cccbe31644726868ee5ac2bec
Cr-Commit-Position: refs/heads/master@{#296072}

[ananta, 2014-09-19 18:48:45]

ananta@chromium.org changed reviewers:
+ sky@chromium.org

[sky, 2014-09-22 14:57:36]

https://codereview.chromium.org/584743004/diff/40001/content/browser/renderer...
File content/browser/renderer_host/render_widget_host_view_aura.cc (right):

https://codereview.chromium.org/584743004/diff/40001/content/browser/renderer...
content/browser/renderer_host/render_widget_host_view_aura.cc:588: if
(GetNativeView()->GetHost()) {
If this isn't true, when does the parent get updated?

[ananta, 2014-09-22 15:12:18]

https://codereview.chromium.org/584743004/diff/40001/content/browser/renderer...
File content/browser/renderer_host/render_widget_host_view_aura.cc (right):

https://codereview.chromium.org/584743004/diff/40001/content/browser/renderer...
content/browser/renderer_host/render_widget_host_view_aura.cc:588: if
(GetNativeView()->GetHost()) {
4On 2014/09/22 14:57:36, sky wrote:
> If this isn't true, when does the parent get updated?

This should not happen with the other change in this patch. Will revert this
file

[ananta, 2014-09-22 18:50:36]

On 2014/09/22 15:12:18, ananta wrote:
>
https://codereview.chromium.org/584743004/diff/40001/content/browser/renderer...
> File content/browser/renderer_host/render_widget_host_view_aura.cc (right):
> 
>
https://codereview.chromium.org/584743004/diff/40001/content/browser/renderer...
> content/browser/renderer_host/render_widget_host_view_aura.cc:588: if
> (GetNativeView()->GetHost()) {
> 4On 2014/09/22 14:57:36, sky wrote:
> > If this isn't true, when does the parent get updated?
> 
> This should not happen with the other change in this patch. Will revert this
> file

Updated the patch with the changes to render_widget_host_view_aura.cc reverted.
PTAL

[sky, 2014-09-22 20:46:28]

LGTM

https://codereview.chromium.org/584743004/diff/60001/ui/views/controls/webvie...
File ui/views/controls/webview/webview.cc (right):

https://codereview.chromium.org/584743004/diff/60001/ui/views/controls/webvie...
ui/views/controls/webview/webview.cc:306: holder_->Attach(view_to_attach);
As order is important, document why.

[ananta, 2014-09-22 21:22:17]

https://codereview.chromium.org/584743004/diff/60001/ui/views/controls/webvie...
File ui/views/controls/webview/webview.cc (right):

https://codereview.chromium.org/584743004/diff/60001/ui/views/controls/webvie...
ui/views/controls/webview/webview.cc:306: holder_->Attach(view_to_attach);
On 2014/09/22 20:46:28, sky wrote:
> As order is important, document why.

Done.

[ananta, 2014-09-22 21:22:53]

The CQ bit was checked by ananta@chromium.org

[commit-bot: I haz the power, 2014-09-22 21:25:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/584743004/80001

[commit-bot: I haz the power, 2014-09-22 22:32:52]

Committed patchset #5 (id:80001) as decc58e81902e5be1226f32850641185f4e3f53c

[commit-bot: I haz the power, 2014-09-22 22:33:23]

Patchset 5 (id:??) landed as
https://crrev.com/d9b817cc6c0f976cccbe31644726868ee5ac2bec
Cr-Commit-Position: refs/heads/master@{#296072}