Bug 1559409 - Show subframe pids in tab hover text, r=mconley

Differential Revision: https://phabricator.services.mozilla.com/D35029

--HG--
extra : moz-landing-system : lando

browser/base/content/tabbrowser.js

@@ -4288,8 +4288,20 @@ window._gBrowser = {
             tab.linkedBrowser.frameLoader) {
           label += " (pid " + tab.linkedBrowser.frameLoader.remoteTab.osPid + ")";
 
-          if (window.docShell.QueryInterface(Ci.nsILoadContext).useRemoteSubframes) {
-            label += " [F]";
+          // If we're running with fission enabled, try to include PID
+          // information for every remote subframe.
+          if (gFissionBrowser) {
+            let pids = new Set();
+            let stack = [tab.linkedBrowser.browsingContext];
+            while (stack.length) {
+              let bc = stack.pop();
+              stack.push(...bc.getChildren());
+              if (bc.currentWindowGlobal) {
+                pids.add(bc.currentWindowGlobal.osPid);
+              }
+            }
+
+            label += " [F " + Array.from(pids).join(", ") + "]";
           }
         }
       }

dom/chrome-webidl/WindowGlobalActors.webidl

@@ -20,6 +20,8 @@ interface WindowGlobalParent {
   readonly attribute unsigned long long outerWindowId;
   readonly attribute unsigned long long contentParentId;
 
+  readonly attribute long osPid;
+
   // A WindowGlobalParent is the root in its process if it has no parent, or its
   // embedder is in a different process.
   readonly attribute boolean isProcessRoot;

dom/ipc/WindowGlobalParent.cpp

@@ -156,6 +156,11 @@ uint64_t WindowGlobalParent::ContentParentId() {
   return browserParent ? browserParent->Manager()->ChildID() : 0;
 }
 
+int32_t WindowGlobalParent::OsPid() {
+  RefPtr<BrowserParent> browserParent = GetBrowserParent();
+  return browserParent ? browserParent->Manager()->Pid() : -1;
+}
+
 // A WindowGlobalPaernt is the root in its process if it has no parent, or its
 // embedder is in a different process.
 bool WindowGlobalParent::IsProcessRoot() {

dom/ipc/WindowGlobalParent.h

@@ -94,6 +94,8 @@ class WindowGlobalParent final : public WindowGlobalActor,
 
   uint64_t ContentParentId();
 
+  int32_t OsPid();
+
   bool IsCurrentGlobal();
 
   bool IsProcessRoot();