Fix multi-arch support for Chrome: start downloading the nexe when SetWindow ...

Fix multi-arch support for Chrome: start downloading the nexe when SetWindow is called instead of doing it during initialization. Note that Firefox does not call SetWindow, so to keep it working we need to handle the "nexes" property at different times in Chrome and in Firefox.
Ideally we will probably want to switch all the tests to use multiarch support, but first we need to get one such test running on Chrome bots (see the link to a Chrome CL below).
BUG=http://code.google.com/p/nativeclient/issues/detail?id=500
TEST=http://codereview.chromium.org/3171010/show



Committed: http://code.google.com/p/nativeclient/source/detail?r=3005

[Mark Seaborn, 2010-08-16 15:13:54]

This seems quite hacky.  Wouldn't it make more sense to fix Chromium so that
NPN_GetURLNotify() works during NPP_New()?  This bug will presumably be an issue
for other plugins.

A reluctant LGTM since #ifs dilute the value of browser-independent tests like
fake_browser_test.

Some nits below...

http://codereview.chromium.org/3145013/diff/7001/8001
File src/trusted/plugin/npapi/plugin_npapi.cc (right):

http://codereview.chromium.org/3145013/diff/7001/8001#newcode176
src/trusted/plugin/npapi/plugin_npapi.cc:176: // to trigger the download if the
src property hasn't been specified.
Can you link to the Chromium bug here?

http://codereview.chromium.org/3145013/diff/7001/8002
File src/trusted/plugin/plugin.cc (right):

http://codereview.chromium.org/3145013/diff/7001/8002#newcode382
src/trusted/plugin/plugin.cc:382: // Firefox allows us to call NPN_GetUrl during
initialization, so if the "src"
Actually it's NPN_GetURLNotify().  Can you update the comment to make it easier
to cross-reference?

[gregoryd, 2010-08-16 18:41:09]

It seems that Chrome people don't think this problem should be fixed on their
side, but I'll check again (after submitting this CL - we would like it to work
in M7)

http://codereview.chromium.org/3145013/diff/7001/8001
File src/trusted/plugin/npapi/plugin_npapi.cc (right):

http://codereview.chromium.org/3145013/diff/7001/8001#newcode176
src/trusted/plugin/npapi/plugin_npapi.cc:176: // to trigger the download if the
src property hasn't been specified.
On 2010/08/16 15:13:59, Mark Seaborn wrote:
> Can you link to the Chromium bug here?

There is no Chromium bug. I spoke to Brett Wilson about it and he suggested that
we change the behavior on our side. It seems that this is yet another issue
where Chrome and Firefox interpret the NPAPI documentation in different ways.

http://codereview.chromium.org/3145013/diff/7001/8002
File src/trusted/plugin/plugin.cc (right):

http://codereview.chromium.org/3145013/diff/7001/8002#newcode382
src/trusted/plugin/plugin.cc:382: // Firefox allows us to call NPN_GetUrl during
initialization, so if the "src"
On 2010/08/16 15:13:59, Mark Seaborn wrote:
> Actually it's NPN_GetURLNotify().  Can you update the comment to make it
easier
> to cross-reference?

Done.