In android_commands.py, surround pexpect import in try-except.

In android_commands.py, surround pexpect import in try-except.

This allows Chrome Remote Control to import this file on platforms like Windows
where pexpect is not available. This works because it never calls the methods
that actually use pexpect.

Example failure:
http://build.chromium.org/p/chromium.perf/builders/Win7%20GPU%20%28Nvidia%29%20Perf/builds/5757/steps/scrolling_benchmark/logs/stdio

BUG=154343
TEST=Manual

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=163395

[Isaac (away), 2012-10-22 21:41:15]

Can't we use the pexpect in third_party/pexpect for all platforms?

[tonyg, 2012-10-22 21:45:21]

On 2012/10/22 21:41:15, Isaac wrote:
> Can't we use the pexpect in third_party/pexpect for all platforms?

Take a look at that stack in the build output link in the change description. It
is using the third_party pexpect, but even that doesn't run on windows.

[Isaac (away), 2012-10-22 21:49:06]

rietveld breaks buildbot links for fun.

lgtm

[bulach, 2012-10-23 10:41:25]

lgtm, but one suggestion:

https://codereview.chromium.org/11234043/diff/1/build/android/pylib/android_c...
File build/android/pylib/android_commands.py (right):

https://codereview.chromium.org/11234043/diff/1/build/android/pylib/android_c...
build/android/pylib/android_commands.py:23: # on platforms without pexpect and
only fail when pexpect is actually used.
nit: nduca added our own wrapper in build/android/pylib/pexpect.py that tries to
load the module..
would it work to add the try..except block directly there instead?

[tonyg, 2012-10-23 15:27:57]

On Tue, Oct 23, 2012 at 3:41 AM,  <bulach@chromium.org> wrote:
> lgtm, but one suggestion:
>
>
>
https://codereview.chromium.org/11234043/diff/1/build/android/pylib/android_c...
> File build/android/pylib/android_commands.py (right):
>
>
https://codereview.chromium.org/11234043/diff/1/build/android/pylib/android_c...
> build/android/pylib/android_commands.py:23: # on platforms without
>
> pexpect and only fail when pexpect is actually used.
> nit: nduca added our own wrapper in build/android/pylib/pexpect.py that
> tries to load the module..
> would it work to add the try..except block directly there instead?

Good idea, but I was too quick with the commit button. Made that
change in https://codereview.chromium.org/11230057/ .

>
> https://codereview.chromium.org/11234043/