Add JavaScript extension point for comments

Plugins can register a JavaScript function that is invoked whenever a
DOM element that represents a comment is created. This DOM element is
passed as argument. This allows the plugin to manipulate the DOM
element, e.g. it can insert images for emoticons or render Markdown.

Change-Id: Ia4f689b0f39ec57ba6835fc4e6a0b32b11c26b07
Signed-off-by: Edwin Kempin <ekempin@google.com>

Documentation/js-api.txt

@@ -176,6 +176,13 @@ Supported events:
   function must return true to allow the operation to continue, or
   false to prevent it.
 
+* `comment`: Invoked when a DOM element that represents a comment is
+  created. This DOM element is passed as argument. This DOM element
+  contains nested elements that Gerrit uses to format the comment. The
+  DOM structure may differ between comment types such as inline
+  comments, file-level comments and summary comments, and it may change
+  with new Gerrit versions.
+
 [[self_onAction]]
 === self.onAction()
 Register a JavaScript callback to be invoked when the user clicks

gerrit-gwtui/src/main/java/com/google/gerrit/client/api/ApiGlue.java

@@ -21,6 +21,7 @@ import com.google.gerrit.client.info.AccountPreferencesInfo;
 import com.google.gerrit.client.info.ServerInfo;
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.JsArray;
+import com.google.gwt.dom.client.Element;
 import com.google.gwt.user.client.History;
 import com.google.gwt.user.client.Window;
 
@@ -296,6 +297,13 @@ public class ApiGlue {
     }
   }
 
+  public static final void fireEvent(String event, Element e) {
+    JsArray<JavaScriptObject> h = getEventHandlers(event);
+    for (int i = 0; i < h.length(); i++) {
+      invoke(h.get(i), e);
+    }
+  }
+
   static final void fireEvent(String event, JavaScriptObject a, JavaScriptObject b) {
     JsArray<JavaScriptObject> h = getEventHandlers(event);
     for (int i = 0; i < h.length(); i++) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/LineComment.java

@@ -15,6 +15,7 @@
 package com.google.gerrit.client.change;
 
 import com.google.gerrit.client.Dispatcher;
+import com.google.gerrit.client.api.ApiGlue;
 import com.google.gerrit.client.changes.CommentInfo;
 import com.google.gerrit.client.diff.DisplaySide;
 import com.google.gerrit.client.ui.CommentLinkProcessor;
@@ -82,6 +83,7 @@ class LineComment extends Composite {
     if (info.message() != null) {
       message.setInnerSafeHtml(clp.apply(new SafeHtmlBuilder()
           .append(info.message().trim()).wikify()));
+      ApiGlue.fireEvent("comment", message);
     }
   }
 

gerrit-gwtui/src/main/java/com/google/gerrit/client/change/Message.java

@@ -17,6 +17,7 @@ package com.google.gerrit.client.change;
 import com.google.gerrit.client.AvatarImage;
 import com.google.gerrit.client.FormatUtil;
 import com.google.gerrit.client.Gerrit;
+import com.google.gerrit.client.api.ApiGlue;
 import com.google.gerrit.client.changes.CommentInfo;
 import com.google.gerrit.client.changes.Util;
 import com.google.gerrit.client.info.ChangeInfo.MessageInfo;
@@ -96,6 +97,7 @@ class Message extends Composite {
       summary.setInnerText(msg);
       message.setInnerSafeHtml(history.getCommentLinkProcessor()
         .apply(new SafeHtmlBuilder().append(msg).wikify()));
+      ApiGlue.fireEvent("comment", message);
     } else {
       reply.getElement().getStyle().setVisibility(Visibility.HIDDEN);
     }

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/PublishedBox.java

@@ -18,6 +18,7 @@ import com.google.gerrit.client.AvatarImage;
 import com.google.gerrit.client.Dispatcher;
 import com.google.gerrit.client.FormatUtil;
 import com.google.gerrit.client.Gerrit;
+import com.google.gerrit.client.api.ApiGlue;
 import com.google.gerrit.client.change.ReplyBox;
 import com.google.gerrit.client.changes.CommentApi;
 import com.google.gerrit.client.changes.CommentInfo;
@@ -100,6 +101,7 @@ class PublishedBox extends CommentBox {
       summary.setInnerText(msg);
       message.setInnerSafeHtml(clp.apply(
           new SafeHtmlBuilder().append(msg).wikify()));
+      ApiGlue.fireEvent("comment", message);
     }
 
     fix.setVisible(open);