default to use --launch-in-chrome with --debug (#276)

Author: jakemac53

webdev/README.md

@@ -58,9 +58,11 @@ Usage: webdev serve [arguments] [<directory>[:<port>]]...
                                   (defaults to "localhost")
 
 
-    --launch-in-chrome            Automatically launches your application in
+    --[no-]launch-in-chrome       Automatically launches your application in
                                   Chrome with the debug port open. Use
-                                  chrome-debug-port to specify a specific port.
+                                  chrome-debug-port to specify a specific port
+                                  to attach to an already running chrome
+                                  instance instead.
 
     --log-requests                Enables logging for each request to the
                                   server.

webdev/lib/src/command/configuration.dart

@@ -148,9 +148,14 @@ class Configuration {
         ? argResults[hostnameFlag] as String
         : defaultConfiguration.hostname;
 
-    var launchInChrome = argResults.options.contains(launchInChromeFlag)
+    var launchInChrome = argResults.options.contains(launchInChromeFlag) &&
+            argResults.wasParsed(launchInChromeFlag)
         ? argResults[launchInChromeFlag] as bool
-        : defaultConfiguration.launchInChrome;
+        // We want to default to launch chrome if the user provides just --debug
+        // and not --chrome-debug-port.
+        : debug && !argResults.wasParsed(chromeDebugPortFlag)
+            ? true
+            : defaultConfiguration.launchInChrome;
 
     var logRequests = argResults.options.contains(logRequestsFlag)
         ? argResults[logRequestsFlag] as bool
@@ -188,8 +193,8 @@ class Configuration {
 
     if (debug && chromeDebugPort == 0 && !launchInChrome) {
       throw InvalidConfiguration(
-          'Must either use --$chromeDebugPortFlag or --$launchInChrome with '
-          '--$debugFlag.');
+          'Must either use --$chromeDebugPortFlag or --$launchInChromeFlag '
+          'with --$debugFlag.');
     }
 
     return Configuration(

webdev/lib/src/command/serve_command.dart

@@ -76,10 +76,9 @@ refresh: Performs a full page refresh.
           hide: true)
       ..addFlag(hotReloadFlag, negatable: false, hide: true)
       ..addFlag(launchInChromeFlag,
-          negatable: false,
           help: 'Automatically launches your application in Chrome with the '
               'debug port open. Use $chromeDebugPortFlag to specify a specific '
-              'port.')
+              'port to attach to an already running chrome instance instead.')
       ..addFlag(liveReloadFlag,
           negatable: false,
           help: