AU: Full proxy support

This CL Introduces a new proxy resolver that queries Chrome browser
for all URLs. This means the updater now works with Proxy
AutoConfiguration (PAC) files and automatic proxy detection.

BUG=chromium-os:9478
TEST=performed update, unittests

Review URL: http://codereview.chromium.org/6594025

Change-Id: I2c169aec06109e3eabc4011e0b536685dfd13f79
diff --git a/update_attempter_mock.h b/update_attempter_mock.h
index 908faeb..16c0e11 100644
--- a/update_attempter_mock.h
+++ b/update_attempter_mock.h
@@ -14,12 +14,12 @@
 
 class UpdateAttempterMock : public UpdateAttempter {
  public:
-  UpdateAttempterMock() : UpdateAttempter(NULL, NULL, &dbus_) {}
+  explicit UpdateAttempterMock(MockDbusGlib* dbus)
+      : UpdateAttempter(NULL, NULL, dbus) {}
 
   MOCK_METHOD3(Update, void(const std::string& app_version,
                             const std::string& omaha_url,
                             bool obey_proxies));
-  MockDbusGlib dbus_;
 };
 
 }  // namespace chromeos_update_engine