AU: Don't use network on expensive connection types

AU: Don't use network on expensive connection types

Specifically:

- FlimFlam proxy class to query the current network status and find
out if it's expensive.
- Dbus Interface, so dbus can be mocked.
- Libcurl change to redirect the URL if we are on an expensive
connection. This may seem hacky, but the reason I avoided retooling
the whole class is that we may decide that some network usage is
okay on pricy connections. Perhaps it's okay to throttle. So, for
now this is a more minimal change.

BUG=chromium-os:2397
TEST=Unit tests, tested that flimflam proxy works on the device.

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=d57d147

[adlr, 2010-10-21 03:21:40]

Here's the latest version of http://codereview.chromium.org/3313001/show

[petkov, 2010-10-21 05:15:19]

LGTM w/ a couple of questions.

http://codereview.chromium.org/4029002/diff/1/4
File flimflam_proxy.cc (right):

http://codereview.chromium.org/4029002/diff/1/4#newcode134
flimflam_proxy.cc:134: if (value && (type_str = g_value_get_string(value))) {
I'm surprised you don't get a gcc warning here. Maybe add an explicit ((type_str
= ...) != NULL)?

http://codereview.chromium.org/4029002/diff/1/6
File flimflam_proxy_unittest.cc (right):

http://codereview.chromium.org/4029002/diff/1/6#newcode154
flimflam_proxy_unittest.cc:154: //static const char*
StringForConnectionType(NetworkConnectionType type);
remove?

http://codereview.chromium.org/4029002/diff/1/8
File libcurl_http_fetcher.cc (right):

http://codereview.chromium.org/4029002/diff/1/8#newcode79
libcurl_http_fetcher.cc:79: if (ConnectionIsExpensive()) {
If the device switches from WiFi to 3G in the middle of a download, does the
connection always fail (as reported by libcurl) so we go through resume again?

[adlr, 2010-10-21 19:41:14]

made fixes. will submit when tree opens.

http://codereview.chromium.org/4029002/diff/1/4
File flimflam_proxy.cc (right):

http://codereview.chromium.org/4029002/diff/1/4#newcode134
flimflam_proxy.cc:134: if (value && (type_str = g_value_get_string(value))) {
On 2010/10/21 05:15:19, petkov wrote:
> I'm surprised you don't get a gcc warning here. Maybe add an explicit
((type_str
> = ...) != NULL)?
> 

Done.

http://codereview.chromium.org/4029002/diff/1/6
File flimflam_proxy_unittest.cc (right):

http://codereview.chromium.org/4029002/diff/1/6#newcode154
flimflam_proxy_unittest.cc:154: //static const char*
StringForConnectionType(NetworkConnectionType type);
On 2010/10/21 05:15:19, petkov wrote:
> remove?
> 

Done.

http://codereview.chromium.org/4029002/diff/1/8
File libcurl_http_fetcher.cc (right):

http://codereview.chromium.org/4029002/diff/1/8#newcode79
libcurl_http_fetcher.cc:79: if (ConnectionIsExpensive()) {
On 2010/10/21 05:15:19, petkov wrote:
> If the device switches from WiFi to 3G in the middle of a download, does the
> connection always fail (as reported by libcurl) so we go through resume again?
> 

This code path is called for every connection or reconnection attempt. So if we
switch connection types midway through a download, it'll handle it properly.