Try again: Add proxy config (using gnome-network-preferences)

BUG=11507
TEST=Open options, click change proxy, gnome-network-preferences should launch.  If gnome isn't installed or running, LinuxProxyConfig wiki page should load.

Review URL: http://codereview.chromium.org/155792

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21246 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: 87fc168b364ef36033f72e545a4894bd7ce9354f
diff --git a/base/linux_util.h b/base/linux_util.h
index 973a2b0..5a46481 100644
--- a/base/linux_util.h
+++ b/base/linux_util.h
@@ -20,6 +20,24 @@
 // GetWinVersion() in base/win_util.h.
 std::string GetLinuxDistro();
 
+// These are used to derive mocks for unittests.
+class EnvironmentVariableGetter {
+ public:
+  virtual ~EnvironmentVariableGetter() {}
+  // Gets an environment variable's value and stores it in
+  // result. Returns false if the key is unset.
+  virtual bool Getenv(const char* variable_name, std::string* result) = 0;
+
+  // Create an instance of EnvironmentVariableGetter
+  static EnvironmentVariableGetter* Create();
+};
+
+// Return true if we appear to be running under Gnome and should attempt to use
+// some prefrences from the desktop environment (eg proxy settings),
+// If someone adds support for other environments, this function could be
+// replaced with one that returns an enum so we an specify Gnome, KDE, etc.
+bool UseGnomeForSettings(EnvironmentVariableGetter* env_var_getter);
+
 }  // namespace base
 
 #endif  // BASE_LINUX_UTIL_H__