Add update manifest for Firefox WebExtension.

Makefile

@@ -87,7 +87,7 @@ crx_contents := script.js eventPage.js icon16.png icon48.png icon128.png manifes
 
 release := \
  $(foreach f, \
-  $(foreach c,. -beta.,$(name)$(c)crx updates$(c)xml $(name)$(c)user.js $(name)$(c)meta.js) \
+  $(foreach c,. -beta.,$(name)$(c)crx updates$(c)xml updates$(c)json $(name)$(c)user.js $(name)$(c)meta.js) \
   $(name)-noupdate.crx \
   $(name)-noupdate.user.js \
   $(name).zip \
@@ -184,6 +184,9 @@ testbuilds/crx$1/manifest.json : src/meta/manifest.json version.json $(template_
 testbuilds/updates$1.xml : src/meta/updates.xml version.json $(template_deps) | testbuilds/crx$1
 	$(template) $$< $$@ type=crx channel=$1
 
+testbuilds/updates$1.json : src/meta/updates.json version.json $(template_deps) | testbuilds/crx$1
+	$(template) $$< $$@ type=crx channel=$1
+
 testbuilds/$(name)$1.crx.zip : \
  $(foreach f,$(crx_contents),testbuilds/crx$1/$(f)) \
  package.json version.json tools/zip-crx.js node_modules/jszip/package.json
@@ -342,7 +345,7 @@ stable : distready
 	git push . HEAD:bstable
 	git tag -af stable -m "$(meta_name) v$(version)."
 	cd dist && git merge --no-commit -s ours stable
-	cd dist && git checkout stable "builds/$(name).*" builds/updates.xml
+	cd dist && git checkout stable "builds/$(name).*" builds/updates.xml builds/updates.json
 	cd dist && git commit -am "Move $(meta_name) v$(version) to stable channel."
 
 web : index.html distready

src/meta/manifest.json

@@ -29,7 +29,8 @@
   ],
   "applications": {
     "gecko": {
-      "id": "<%= meta.appidGecko %>"
-    }
+      "id": "<%= meta.appidGecko %>"<% if (channel !== '-noupdate') { %>,
+      "update_url": "<%= meta.downloads %>updates<%= channel %>.json"
+<% } %>    }
   }
 }

src/meta/updates.json

@@ -0,0 +1,12 @@
+{
+  "addons": {
+    "<%= meta.appidGecko %>": {
+      "updates": [
+        {
+          "version": "<%= readJSON('/version.json').version %>",
+          "update_link": "<%= meta.downloads %><%= name %><%= channel %>.crx"
+        }
+      ]
+    }
+  }
+}