Bug 1195018 - Support 'background_color' member in the manifest processor. r=marcosc

dom/manifest/ManifestProcessor.jsm

@@ -90,6 +90,7 @@ this.ManifestProcessor = { // jshint ignore:line
       ),
       'short_name': processShortNameMember(),
       'theme_color': processThemeColorMember(),
+      'background_color': processBackgroundColorMember(),
     };
     processedManifest.scope = processScopeMember();
     return processedManifest;
@@ -224,6 +225,17 @@ this.ManifestProcessor = { // jshint ignore:line
       return extractor.extractColorValue(spec);
     }
 
+    function processBackgroundColorMember() {
+      const spec = {
+        objectName: 'manifest',
+        object: rawManifest,
+        property: 'background_color',
+        expectedType: 'string',
+        trim: true
+      };
+      return extractor.extractColorValue(spec);
+    }
+
     function processLangMember() {
       const spec = {
         objectName: 'manifest',

dom/manifest/ValueExtractor.jsm

@@ -53,7 +53,7 @@ ValueExtractor.prototype = {
     if (DOMUtils.isValidCSSColor(value)) {
       color = value;
     } else if (value) {
-      const msg = `background_color: ${value} is not a valid CSS color.`;
+      const msg = `${spec.property}: ${value} is not a valid CSS color.`;
       this.console.warn(msg);
     }
     return color;