Add new chrome://proximity-auth WebUI for debugging Smart Lock.

components/proximity_auth/webui/resources/proximity_auth.js

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// TODO(tengs): This page is just a placeholder. The real page still needs to be
+// built.
+
+function LSystem(rules, startState, iterations) {
+  symbols = startState.split('').map(function(character) {
+    return { c: character, i: 0 };
+  });
+
+  while (true) {
+    var index = -1;
+    for (var i = 0; i < symbols.length; ++i) {
+      var symbol = symbols[i];
+      if (symbol.i < iterations && rules[symbol.c] != null) {
+        index = i;
+        break;
+      }
+    }
+    if (index == -1)
+      break;
+
+    var symbol = symbols[index];
+    var newSymbols = rules[symbol.c].apply(symbol).split('').map(function(c) {
+      return { c: c, i: symbol.i + 1 };
+    });
+
+    Array.prototype.splice.apply(symbols, [index, 1].concat(newSymbols));
+  }
+
+  return symbols.map(function(symbol) {
+    return symbol.c;
+  });
+};
+
+var rules = {
+  'X': function(x) { return 'X+YF'; },
+  'Y': function(y) { return 'FX-Y'; },
+}
+var startState = 'FX+FX+';
+var iterations = 10;
+
+function draw() {
+  var canvas = document.getElementById('canvas');
+  canvas.width = canvas.offsetWidth;
+  canvas.height = canvas.offsetHeight;
+
+  var canvasWidth = canvas.offsetWidth;
+  var canvasHeight = canvas.offsetHeight;
+  var context = canvas.getContext('2d');
+
+  context.lineWidth = 2;
+  var segmentWidth = 0.015 * canvasHeight;
+  var pos = {
+    x: 0.5 * canvasWidth,
+    y: 0.25 * canvasHeight,
+  };
+  var dir = { x: 1, y: 0, };
+
+  var commands = LSystem(rules, startState, iterations);
+  var drawCommand = function() {
+    var command = commands.shift();
+    if (command === 'F') {
+      context.beginPath();
+      context.moveTo(pos.x, pos.y);
+
+      pos = {
+        x: pos.x + dir.x * segmentWidth,
+        y: pos.y + dir.y * segmentWidth,
+      };
+
+      context.lineTo(pos.x, pos.y);
+      var r = Math.round(pos.x / canvasWidth * 256);
+      var b = Math.round(pos.y / canvasHeight * 256);
+      var g = 180;
+      context.strokeStyle = 'rgb(' + r + ',' + g + ',' + b + ')';
+      context.stroke();
+    } else if (command === '+') {
+      dir = { x: -dir.y, y: dir.x }
+    } else if (command === '-') {
+      dir = { x: dir.y, y: -dir.x }
+    }
+  }
+
+  window.setInterval(drawCommand, 10);
+  //while (commands.length) drawCommand();
+}
+
+document.addEventListener("DOMContentLoaded", draw);

[Ilya Sherman, 2015/04/14 00:25:44]

Can we leave this file essentially empty, rather than creating this ad-hoc
implementation that's not meant to last long-term?  I'd rather not review this
code, which is fairly conceptually dense, if it's not going to last; but we also
shouldn't check in unreviewed code.

[Tim Song, 2015/04/14 06:00:12]

This is a placeholder to confirm that chrome://proximity-auth indeed loads
something. As just some arbitrary sandboxed JS, I think we're fine without a
review. Plus, it looks really cool.