Add a highlight.js loaded hook This event allows plugins to listen for the loading of the HLJS library so that they can install custom language definitions or otherwise change highlighting behavior. Change-Id: Id3e55e3d7bc1421a5b8564846901ab9b69146cbd

diff --git a/Documentation/js-api.txt b/Documentation/js-api.txt
index 96b5107..4ef2a6c 100644
--- a/Documentation/js-api.txt
+++ b/Documentation/js-api.txt

@@ -188,6 +188,12 @@
   comments, file-level comments and summary comments, and it may change
   with new Gerrit versions.
 
+* `highlightjs-loaded`: Invoked when the highlight.js library has
+  finished loading. The global `hljs` object (also now accessible via
+  `window.hljs`) is passed as an argument to the callback function.
+  This event can be used to register a new language highlighter with
+  the highlight.js library before syntax highlighting begins.
+
 [[self_onAction]]
 === self.onAction()
 Register a JavaScript callback to be invoked when the user clicks

diff --git a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
index f5026fe..fe5d427 100644
--- a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
+++ b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js

@@ -83,6 +83,7 @@
     'text/x-swift': 'swift',
     'text/x-systemverilog': 'sv',
     'text/x-tcl': 'tcl',
+    'text/x-torque': 'torque',
     'text/x-twig': 'twig',
     'text/x-vb': 'vb',
     'text/x-verilog': 'v',

diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface.js b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface.js
index 820d2c0..f981c99 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface.js
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface.js

@@ -28,6 +28,7 @@
     POST_REVERT: 'postrevert',
     ANNOTATE_DIFF: 'annotatediff',
     ADMIN_MENU_LINKS: 'admin-menu-links',
+    HIGHLIGHTJS_LOADED: 'highlightjs-loaded',
   };
 
   const Element = {
@@ -69,6 +70,9 @@
           case EventType.LABEL_CHANGE:
             this._handleLabelChange(detail);
             break;
+          case EventType.HIGHLIGHTJS_LOADED:
+            this._handleHighlightjsLoaded(detail);
+            break;
           default:
             console.warn('handleEvent called with unsupported event type:',
                 type);
@@ -188,6 +192,16 @@
       }
     },
 
+    _handleHighlightjsLoaded(detail) {
+      for (const cb of this._getEventCallbacks(EventType.HIGHLIGHTJS_LOADED)) {
+        try {
+          cb(detail.hljs);
+        } catch (err) {
+          console.error(err);
+        }
+      }
+    },
+
     modifyRevertMsg(change, revertMsg, origMsg) {
       for (const cb of this._getEventCallbacks(EventType.REVERT)) {
         try {

diff --git a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html
index 54c283d..113a6f7 100644
--- a/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html
+++ b/polygerrit-ui/app/elements/shared/gr-js-api-interface/gr-js-api-interface_test.html

@@ -300,6 +300,17 @@
       assert.isTrue(errorStub.calledTwice);
     });
 
+    test('highlightjs-loaded event', done => {
+      const testHljs = {_number: 42};
+      plugin.on(element.EventType.HIGHLIGHTJS_LOADED, throwErrFn);
+      plugin.on(element.EventType.HIGHLIGHTJS_LOADED, hljs => {
+        assert.deepEqual(hljs, testHljs);
+        assert.isTrue(errorStub.calledOnce);
+        done();
+      });
+      element.handleEvent(element.EventType.HIGHLIGHTJS_LOADED, {hljs: testHljs});
+    });
+
     test('versioning', () => {
       const callback = sandbox.spy();
       Gerrit.install(callback, '0.0pre-alpha');

diff --git a/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.html b/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.html
index f70aff4..4137485 100644
--- a/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.html
+++ b/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.html

@@ -15,7 +15,11 @@
 limitations under the License.
 -->
 <link rel="import" href="../../../bower_components/polymer/polymer.html">
+<link rel="import" href="../../shared/gr-js-api-interface/gr-js-api-interface.html">
 
 <dom-module id="gr-lib-loader">
+  <template>
+    <gr-js-api-interface id="jsAPI"></gr-js-api-interface>
+  </template>
   <script src="gr-lib-loader.js"></script>
 </dom-module>

diff --git a/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.js b/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.js
index ef8c112..478c619 100644
--- a/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.js
+++ b/polygerrit-ui/app/elements/shared/gr-lib-loader/gr-lib-loader.js

@@ -82,6 +82,9 @@
     _onHLJSLibLoaded() {
       const lib = this._getHighlightLib();
       this._hljsState.loading = false;
+      this.$.jsAPI.handleEvent(this.$.jsAPI.EventType.HIGHLIGHTJS_LOADED, {
+        hljs: lib,
+      });
       for (const cb of this._hljsState.callbacks) {
         cb(lib);
       }