Make the terminal demo able (to try) to connect to anything.

(Using the query string from the URL.)

R=erg@chromium.org

Review URL: https://codereview.chromium.org/1019323002

examples/terminal/index.sky

@@ -5,4 +5,22 @@
 // found in the LICENSE file.
 -->
 <import src="terminal.sky" />
-<terminal url="mojo:echo_terminal" />
+<!--
+<terminal id="terminal" url="mojo:echo_terminal" />
+-->
+<terminal id="terminal" />
+<script>
+import 'dart:core';
+import 'dart:sky';
+
+main () {
+  var terminal = document.getElementById('terminal');
+  var params = Uri.parse(document.URL).queryParameters;
+  if (params.containsKey('url')) {
+    terminal.connect(params['url']);
+  } else {
+    terminal.putString('HALP: Add a "?url=<URL>" query.\n'
+                       'E.g., "?url=mojo:echo_terminal".\n');
+  }
+}
+</script>

examples/terminal/terminal.sky

@@ -13,9 +13,10 @@
       background-color: black;
       color: rgb(255, 191, 0);
       font-family: 'Courier', 'monospace';
+      font-size: small;
     }
     .line {
-      white-space: pre;
+      white-space: nowrap;
     }
   </style>
   <sky-scrollable id="control" contenteditable />
@@ -60,7 +61,10 @@ class TerminalDisplayImpl extends SkyElement implements TerminalDisplay {
     // Initialize with the first line.
     _newLine();
 
-    _connect(getAttribute('url'));
+    var url = getAttribute('url');
+    if (url != null) {
+      connect(url);
+    }
   }
 
   void _handleKeyDown(KeyboardEvent event) {
@@ -111,15 +115,19 @@ class TerminalDisplayImpl extends SkyElement implements TerminalDisplay {
     _newLine();
   }
 
-  // TODO(vtl): Should we always auto-connect? Should there be facilities for
-  // programmatically connecting? (What if the |url| attribute isn't set?)
-  void _connect(String url) {
+  void connect(String url) {
     var terminalClient = new terminal.TerminalClientProxy.unbound();
     embedder.connectToService(url, terminalClient);
     terminalClient.ptr.connectToTerminal(new TerminalFileImpl(this).stub);
     terminalClient.close();
   }
 
+  void putString(String s) {
+    for (var i = 0; i < s.length; i++) {
+      putChar(s.codeUnitAt(i));
+    }
+  }
+
   // |TerminalDisplay| implementation:
 
   @override