Fix renderer process host backgrounding test on Windows.

Fix renderer process host backgrounding test on Windows.

Now that process backgrounding is controlled from within the renderer
process on Windows, we need to wait for the process to handle the IPC
message before the background state changes.

This fix changes the test to wait for the result of a script from
the renderer process before checking background status.  Doing so
ensures the renderer will process the background IPC before the
check is performed.

BUG=362294
TEST=Ran unittest on Windows.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=274778

[DaleCurtis, 2014-06-02 22:39:04]

This re-enables the test disabled in https://codereview.chromium.org/305533006/

Please let me know if there's a better way to do this.  I couldn't find a
notification to subscribe to which would accomplish waiting for the renderer
process to process an IPC message reliably.

[jam, 2014-06-03 21:51:43]

On 2014/06/02 22:39:04, DaleCurtis wrote:
> This re-enables the test disabled in
https://codereview.chromium.org/305533006/
> 
> Please let me know if there's a better way to do this.  I couldn't find a
> notification to subscribe to which would accomplish waiting for the renderer
> process to process an IPC message reliably.

as a rule of thumb, we avoid tests that poll for an event.

in this case, it seems you can use one of the content::ExecuteScript* methods to
run script and wait for the result. since that ipc would be sent after the
backgrounded-ipc, that should ensure you wait for the renderer to run that code

[DaleCurtis, 2014-06-03 22:49:30]

Thanks for the suggestion, that's exactly what I was looking for.  Patch
updated.

[jam, 2014-06-04 01:06:05]

lgtm with nit

https://codereview.chromium.org/305373004/diff/40001/chrome/browser/renderer_...
File chrome/browser/renderer_host/render_process_host_chrome_browsertest.cc
(right):

https://codereview.chromium.org/305373004/diff/40001/chrome/browser/renderer_...
chrome/browser/renderer_host/render_process_host_chrome_browsertest.cc:105: //
messages by running some JavaScript and waiting for the result.
this comment is a bit misleading; afaik you're waiting for the renderer to
process an IPC, and not a WebContents (browser process) right? if so, adjust the
comment to say that this ensures that the renderer processed the IPC to set
itself to be backgrounded

[DaleCurtis, 2014-06-04 01:10:18]

https://codereview.chromium.org/305373004/diff/40001/chrome/browser/renderer_...
File chrome/browser/renderer_host/render_process_host_chrome_browsertest.cc
(right):

https://codereview.chromium.org/305373004/diff/40001/chrome/browser/renderer_...
chrome/browser/renderer_host/render_process_host_chrome_browsertest.cc:105: //
messages by running some JavaScript and waiting for the result.
On 2014/06/04 01:06:05, jam wrote:
> this comment is a bit misleading; afaik you're waiting for the renderer to
> process an IPC, and not a WebContents (browser process) right? if so, adjust
the
> comment to say that this ensures that the renderer processed the IPC to set
> itself to be backgrounded

Done.

[DaleCurtis, 2014-06-04 01:23:20]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2014-06-04 01:24:43]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dalecurtis@chromium.org/305373004/60001

[commit-bot: I haz the power, 2014-06-04 11:34:55]

Change committed as 274778