From 2ae4d6a15b6706e9d9863b2d50223dcfefaae69e Mon Sep 17 00:00:00 2001
From: Neil Deakin <neil@mozilla.com>
Date: Thu, 21 Jan 2021 08:44:51 +0000
Subject: [PATCH] Bug 1644911, add access to the childID from the frame crashed
 event, r=nika

Differential Revision: https://phabricator.services.mozilla.com/D98206
---
 dom/base/nsFrameLoader.cpp               | 4 +++-
 dom/base/nsFrameLoader.h                 | 2 ++
 dom/ipc/BrowserParent.cpp                | 3 ++-
 dom/ipc/tests/browser_crash_oopiframe.js | 1 +
 dom/webidl/FrameCrashedEvent.webidl      | 8 ++++++++
 5 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/dom/base/nsFrameLoader.cpp b/dom/base/nsFrameLoader.cpp
index 41933fad197b..37d7ef874098 100644
--- a/dom/base/nsFrameLoader.cpp
+++ b/dom/base/nsFrameLoader.cpp
@@ -2672,7 +2672,7 @@ bool nsFrameLoader::TryRemoteBrowser() {
   // Check if we should report a browser-crashed error because the browser
   // failed to start.
   if (XRE_IsParentProcess() && mOwnerContent && mOwnerContent->IsXULElement()) {
-    MaybeNotifyCrashed(nullptr, nullptr);
+    MaybeNotifyCrashed(nullptr, ContentParentId(), nullptr);
   }
 
   return false;
@@ -3684,6 +3684,7 @@ void nsFrameLoader::SetWillChangeProcess() {
 }
 
 void nsFrameLoader::MaybeNotifyCrashed(BrowsingContext* aBrowsingContext,
+                                       ContentParentId aChildID,
                                        mozilla::ipc::MessageChannel* aChannel) {
   if (mTabProcessCrashFired) {
     return;
@@ -3731,6 +3732,7 @@ void nsFrameLoader::MaybeNotifyCrashed(BrowsingContext* aBrowsingContext,
   if (aBrowsingContext) {
     init.mBrowsingContextId = aBrowsingContext->Id();
     init.mIsTopFrame = aBrowsingContext->IsTop();
+    init.mChildID = aChildID;
   }
 
   RefPtr<FrameCrashedEvent> event = FrameCrashedEvent::Constructor(
diff --git a/dom/base/nsFrameLoader.h b/dom/base/nsFrameLoader.h
index a432b660f1e9..ed5ab61934c8 100644
--- a/dom/base/nsFrameLoader.h
+++ b/dom/base/nsFrameLoader.h
@@ -24,6 +24,7 @@
 #include "mozilla/dom/Nullable.h"
 #include "mozilla/dom/Promise.h"
 #include "mozilla/dom/WindowProxyHolder.h"
+#include "mozilla/dom/ipc/IdType.h"
 #include "mozilla/layers/LayersTypes.h"
 #include "nsCOMPtr.h"
 #include "nsCycleCollectionParticipant.h"
@@ -410,6 +411,7 @@ class nsFrameLoader final : public nsStubMutationObserver,
                            mozilla::dom::ContentParent* aContentParent);
 
   void MaybeNotifyCrashed(mozilla::dom::BrowsingContext* aBrowsingContext,
+                          mozilla::dom::ContentParentId aChildID,
                           mozilla::ipc::MessageChannel* aChannel);
 
   void FireErrorEvent();
diff --git a/dom/ipc/BrowserParent.cpp b/dom/ipc/BrowserParent.cpp
index 3b03d9fcd2c7..5ede68022d04 100644
--- a/dom/ipc/BrowserParent.cpp
+++ b/dom/ipc/BrowserParent.cpp
@@ -742,7 +742,8 @@ void BrowserParent::ActorDestroy(ActorDestroyReason why) {
 
     // If this was a crash, tell our nsFrameLoader to fire crash events.
     if (why == AbnormalShutdown) {
-      frameLoader->MaybeNotifyCrashed(mBrowsingContext, GetIPCChannel());
+      frameLoader->MaybeNotifyCrashed(mBrowsingContext, Manager()->ChildID(),
+                                      GetIPCChannel());
 
       auto* bridge = GetBrowserBridgeParent();
       if (bridge && bridge->CanSend() && !mBrowsingContext->IsDiscarded()) {
diff --git a/dom/ipc/tests/browser_crash_oopiframe.js b/dom/ipc/tests/browser_crash_oopiframe.js
index 68d1994a4675..6d134b40ffa5 100644
--- a/dom/ipc/tests/browser_crash_oopiframe.js
+++ b/dom/ipc/tests/browser_crash_oopiframe.js
@@ -51,6 +51,7 @@ add_task(async function() {
       info("Waiting for oop-browser-crashed event.");
       await eventFiredPromise.then(event => {
         ok(!event.isTopFrame, "should not be reporting top-level frame crash");
+        ok(event.childID != 0, "childID is non-zero");
 
         isnot(
           event.browsingContextId,
diff --git a/dom/webidl/FrameCrashedEvent.webidl b/dom/webidl/FrameCrashedEvent.webidl
index 234649b29704..b6d88f275763 100644
--- a/dom/webidl/FrameCrashedEvent.webidl
+++ b/dom/webidl/FrameCrashedEvent.webidl
@@ -20,10 +20,18 @@ interface FrameCrashedEvent : Event
    * True if the top-most frame crashed.
    */
   readonly attribute boolean isTopFrame;
+
+  /**
+   * Internal process identifier of the frame that crashed. This will be
+   * 0 if this identifier is not known, for example a process that failed
+   * to start.
+   */
+  readonly attribute unsigned long long childID;
 };
 
 dictionary FrameCrashedEventInit : EventInit
 {
   unsigned long long browsingContextId = 0;
   boolean isTopFrame = true;
+  unsigned long long childID = 0;
 };