DevTools: introduce spritesheet assembler.

third_party/WebKit/Source/devtools/scripts/spritesheet_assembler/DevToolsDescriptors.js

+var path = require('path');
+
+var licenseHeader = [
+  '// Copyright 2017 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.'
+].join('\n');
+
+var generatedFileNotice = ['/**', ' * NOTICE: This file was generated by spritesheet_assembler.', ' */'].join('\n');
+
+
+var DevToolsDescriptors = {
+  /**
+   * @param {!SVGSpriteSheet} spriteSheet
+   * @return {string}
+   */
+  generateJS: function(spriteSheet) {
+    // Manually craft json which alines with our style.
+    var json = 'UI.Icon.setSpriteSheet({';
+    json += `\n  size: '${spriteSheet.width()}px ${spriteSheet.height()}px',`;
+    json += '\n  descriptors: {';
+    for (var sprite of spriteSheet.sprites()) {
+      var extension = path.extname(sprite.filePath);
+      var spriteName = path.basename(sprite.filePath, extension);
+      var isMask = false;
+      if (spriteName.endsWith('-mask')) {
+        spriteName = spriteName.replace(/-mask$/, '');
+        isMask = true;
+      }
+      var descriptor = `'${spriteName}': {`;
+      var position = spriteSheet.spritePosition(sprite);
+      descriptor += 'x: ' + (-position.x);
+      descriptor += ', y: ' + (-position.y);
+      descriptor += ', width: ' + sprite.width;
+      descriptor += ', height: ' + sprite.height;
+      if (isMask)
+        descriptor += ', isMask: ' + isMask;
+      descriptor += '},';
+      json += '\n    ' + descriptor;
+    }
+    json += '\n  }';
+    json += '\n});';
+    var fileHeader = licenseHeader + '\n\n' + generatedFileNotice + '\n\n';
+    return fileHeader + json;
+  },
+};
+
+module.exports = DevToolsDescriptors;