Linux: fix crash when renderer asks for the location of a NULL window

Linux: fix crash when renderer asks for the location of a NULL window

There are cases where the renderer asks for the root rectangle of its
window before we have a window for it. Since we still have the
NativeViewId hack in place, this previously caused a crash.

[Avi (use Gerrit), 2009-03-18 21:09:32]

http://codereview.chromium.org/42356/diff/1/2
File chrome/browser/renderer_host/resource_message_filter.cc (right):

http://codereview.chromium.org/42356/diff/1/2#newcode571
Line 571: *rect = gfx::Rect(0, 0, 0, 0);
1. The default constructor for gfx::Rect will do this.
2. This code is out of date; I split this function into three files earlier
today.

[Craig Schlenter, 2009-03-19 05:05:50]

This bug is my fault :( I didn't anticipate being passed a null window. I did a
similar fix here:
http://codereview.chromium.org/42229/show
I wasn't sure if returning 0 would be acceptable since I hadn't dug into the
code in detail so I returned the root window rectangle.