Fix double delete of ImageLoadingTracker in BrowserActionButton.

Fix memory stomping by ImageLoadingTracker in BrowserActionButton.

In the views code, tracker_ is set to null in this case.  Without
this, I get lots of random crashes when I have 2 page actions
installed (buildbot extension and google tasks extension) and I open
close lots of windows.

BUG=26751, 25558
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=31534

[Evan Stade, 2009-11-10 01:51:19]

LGTM!

nit: concerning the change description, is this really a double free, or is it
just that we setting some random memory to NULL because the pointer is stale?

[tony, 2009-11-10 01:54:57]

On 2009/11/10 01:51:19, Evan Stade wrote:
> LGTM!
> 
> nit: concerning the change description, is this really a double free, or is it
> just that we setting some random memory to NULL because the pointer is stale?

Yes, you're right.  I thought StopTrackingImageLoad did a delete, but it
doesn't.  It's just stomping memory by setting observer_ to NULL.  Description
updated.

[Aaron Boodman, 2009-11-10 01:56:57]

Makes sense :( LGTM.