untested browser opening on Android

I've found multiple references to using the `am` command from the adb shell
to open a browser. So I assume it also works in a terminal emulator.

Command/WebApp.hs

@@ -150,7 +150,7 @@ firstRun listenhost = do
 	sendurlback v _origout _origerr url _htmlshim = putMVar v url
 
 openBrowser :: Maybe FilePath -> FilePath -> Maybe Handle -> Maybe Handle -> IO ()
-openBrowser cmd htmlshim outh errh = do
+openBrowser mcmd htmlshim outh errh = do
 	hPutStrLn (fromMaybe stdout outh) $ "Launching web browser on " ++ url
 	environ <- cleanEnvironment
 	(_, _, _, pid) <- createProcess p
@@ -163,7 +163,9 @@ openBrowser cmd htmlshim outh errh = do
 		hPutStrLn (fromMaybe stderr errh) "failed to start web browser"
   where
 	url = fileUrl htmlshim
-	p = proc (fromMaybe browserCommand cmd) [htmlshim]
+	p = case mcmd of
+		Just cmd -> proc cmd [htmlshim]
+		Nothing -> browserProc htmlshim
 
 {- web.browser is a generic git config setting for a web browser program -}
 webBrowser :: Git.Repo -> Maybe FilePath

Utility/WebApp.hs

@@ -40,12 +40,17 @@ import Control.Concurrent
 localhost :: HostName
 localhost = "localhost"
 
-{- Command to use to run a web browser. -}
-browserCommand :: FilePath
+{- Builds a command to use to start or open a web browser showing an url. -}
+browserProc :: String -> CreateProcess
 #ifdef darwin_HOST_OS
-browserCommand = "open"
+browserProc url = proc "open" [url]
 #else
-browserCommand = "xdg-open"
+#ifdef __ANDROID__
+browserProc url = proc "am"
+	["start", "-a", "android.intent.action.VIEW", "-d", url]
+#else
+browserProc url = proc "xdg-open" [url]
+#endif
 #endif
 
 {- Binds to a socket on localhost, or possibly a different specified