Bug 1455479 - Show paste context menu item when there are paste event listeners. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D97751

browser/actors/ContextMenuChild.jsm

@@ -924,6 +924,17 @@ class ContextMenuChild extends JSWindowActorChild {
     context.shouldInitInlineSpellCheckerUINoChildren = false;
     context.shouldInitInlineSpellCheckerUIWithChildren = false;
 
+    context.hasPasteEventListeners = (function() {
+      let els = Services.els;
+      const composed = false; // Paste event listener is not composed.
+      for (let item of els.getEventTargetChainFor(context.target, composed)) {
+        if (els.hasListenersFor(item, "paste")) {
+          return true;
+        }
+      }
+      return false;
+    })();
+
     this._setContextForNodesNoChildren(editFlags);
     this._setContextForNodesWithChildren(editFlags);
 

browser/base/content/nsContextMenu.js

@@ -228,6 +228,7 @@ class nsContextMenu {
     this.onSpellcheckable = context.onSpellcheckable;
     this.onTextInput = context.onTextInput;
     this.onVideo = context.onVideo;
+    this.hasPasteEventListeners = context.hasPasteEventListeners;
 
     this.target = context.target;
     this.targetIdentifier = context.targetIdentifier;
@@ -445,6 +446,7 @@ class nsContextMenu {
       this.onTextInput ||
       this.onLink ||
       this.isContentSelected ||
+      this.hasPasteEventListeners ||
       this.onImage ||
       this.onCanvas ||
       this.onVideo ||
@@ -756,9 +758,15 @@ class nsContextMenu {
     this.showItem("context-sep-undo", this.onTextInput);
     this.showItem("context-cut", this.onTextInput);
     this.showItem("context-copy", this.isContentSelected || this.onTextInput);
-    this.showItem("context-paste", this.onTextInput);
+    this.showItem(
+      "context-paste",
+      this.hasPasteEventListeners || this.onTextInput
+    );
     this.showItem("context-delete", this.onTextInput);
-    this.showItem("context-sep-paste", this.onTextInput);
+    this.showItem(
+      "context-sep-paste",
+      this.hasPasteEventListeners || this.onTextInput
+    );
     this.showItem(
       "context-selectall",
       !(

browser/base/content/test/contextMenu/browser_contextmenu.js

@@ -271,6 +271,51 @@ add_task(async function test_mailto() {
   ]);
 });
 
+add_task(async function test_paste_event_listener() {
+  const expected = [
+    "context-navigation",
+    null,
+    [
+      "context-back",
+      false,
+      "context-forward",
+      false,
+      "context-reload",
+      true,
+      "context-bookmarkpage",
+      true,
+    ],
+    null,
+    "---",
+    null,
+    ...(hasPocket ? ["context-pocket", true] : []),
+    "---",
+    null,
+    "context-sendpagetodevice",
+    true,
+    [],
+    null,
+    "---",
+    null,
+    "context-viewbgimage",
+    false,
+    "context-paste",
+    null,
+    "---",
+    null,
+    "context-selectall",
+    true,
+    "---",
+    null,
+    "context-viewsource",
+    true,
+    "context-viewinfo",
+    true,
+  ];
+  await test_contextmenu("#test-paste-listener", expected);
+  await test_contextmenu("#test-paste-listener-child", expected);
+});
+
 add_task(async function test_image() {
   for (let selector of ["#test-image", "#test-svg-image"]) {
     await test_contextmenu(

browser/base/content/test/contextMenu/subtst_contextmenu.html

@@ -17,6 +17,10 @@ if ("ShadowRoot" in this) {
 }
 </script>
 <a id="test-mailto" href="mailto:codemonkey@mozilla.com">Mail the monkey!</a><br>
+<div id="test-paste-listener" onpaste="doSomething()">
+  ABCD
+  <p id="test-paste-listener-child">EFGH</p>
+</div>
 <input id="test-input"><br>
 <img id="test-image" src="ctxmenu-image.png">
 <svg>