Adds --auto_platform to download_from_google_storage.

Adds --auto_platform to download_from_google_storage.

A very common pattern for the users of this script is to have binaries in
three different folders, eg:
some/folder/win/bin.exe
some/folder/mac/bin
some/folder/linux/bin

Instead of using --platform to specify three different paths, we can recognize
this usage and pass in --auto_platform, and then --directory some/folder/ as the
target.

When enumerating files, it will match each individual file to see if they have
(win|mac|linux) as a parent folder name, and filter out non-matching platforms.

BUG=
TEST= src/third_party/clang_format/bin$ download_from_google_storage --auto_platform --no_auth -b chromium-clang-fomat -dr .
0> Downloading ./linux/clang-format...

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=245643

[Ryan Tseng, 2014-01-07 23:59:37]

I realized that almost everyone who uses this uses it for binaries, and almost
always separates it into folder/win, folder/mac, folder/linux so might as well
recognize it.  What do you think?

[Ryan Tseng, 2014-01-17 19:38:42]

ping?

[M-A Ruel, 2014-01-17 20:19:21]

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage.py
File download_from_google_storage.py (right):

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:30: 'darwin': 'mac',
sort keys

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:131: """Check if any parent directory of target
matches (win|mac|linux)."""
Checks

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:134: full_path = os.path.abspath(target)
what about asserting the path is absolute?

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:136: if target_name in ('win', 'mac', 'linux'):
sort

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:138: return check_platform(root)
What happens if you call it with 'e:\\' ?

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:194: err = ('--auto_platform passed in but no '
the wrapping seems excessive, try to extend nearer to 80 cols

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:376: '(win|mac|linux).  If so, the script will
only '
sort

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:388: return 1
parser.error() calls sys.exit(2), no need for return afterward.

[Ryan Tseng, 2014-01-17 20:58:37]

Thanks for the review, comments addressed, please take a look again.

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage.py
File download_from_google_storage.py (right):

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:30: 'darwin': 'mac',
On 2014/01/17 20:19:21, M-A Ruel wrote:
> sort keys

Done.

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:131: """Check if any parent directory of target
matches (win|mac|linux)."""
On 2014/01/17 20:19:21, M-A Ruel wrote:
> Checks

Done.

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:134: full_path = os.path.abspath(target)
On 2014/01/17 20:19:21, M-A Ruel wrote:
> what about asserting the path is absolute?

Done.

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:136: if target_name in ('win', 'mac', 'linux'):
On 2014/01/17 20:19:21, M-A Ruel wrote:
> sort

Done.

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:138: return check_platform(root)
On 2014/01/17 20:19:21, M-A Ruel wrote:
> What happens if you call it with 'e:\\' ?

>>> path.split('e:\\')
('e:\\', '')
>>> os.path.split('/')
('/', '')

Oops this is a bug, fixed

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:194: err = ('--auto_platform passed in but no '
On 2014/01/17 20:19:21, M-A Ruel wrote:
> the wrapping seems excessive, try to extend nearer to 80 cols

Done.

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:376: '(win|mac|linux).  If so, the script will
only '
On 2014/01/17 20:19:21, M-A Ruel wrote:
> sort

Done.

https://codereview.chromium.org/126893002/diff/1/download_from_google_storage...
download_from_google_storage.py:388: return 1
On 2014/01/17 20:19:21, M-A Ruel wrote:
> parser.error() calls sys.exit(2), no need for return afterward.

Done.

[M-A Ruel, 2014-01-17 21:05:02]

lgtm

[commit-bot: I haz the power, 2014-01-17 22:26:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/hinoka@google.com/126893002/150001

[commit-bot: I haz the power, 2014-01-17 22:28:32]

Change committed as 245643