Bug 1560977 - Annotate crash reports if Fission is enabled. r=nika

Differential Revision: https://phabricator.services.mozilla.com/D36530

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

docshell/base/nsDocShell.cpp

@@ -1567,7 +1567,13 @@ nsDocShell::GetUseRemoteSubframes(bool* aUseRemoteSubframes) {
 
 NS_IMETHODIMP
 nsDocShell::SetRemoteSubframes(bool aUseRemoteSubframes) {
-  // Should we annotate crash reports like in aUseRemoteTabs?
+  static bool annotated = false;
+
+  if (aUseRemoteSubframes && !annotated) {
+    annotated = true;
+    CrashReporter::AnnotateCrashReport(CrashReporter::Annotation::DOMFissionEnabled,
+                                       true);
+  }
 
   // Don't allow non-remote tabs with remote subframes.
   if (NS_WARN_IF(aUseRemoteSubframes && !mUseRemoteTabs)) {

toolkit/crashreporter/CrashAnnotations.yaml

@@ -261,6 +261,12 @@ DeviceResetReason:
     Reason why a DirectX device has been reset, Windows only.
   type: string
 
+DOMFissionEnabled:
+  description: >
+    Set to 1 when DOM fission is enabled, and subframes are potentially loaded
+    in a separate process.
+  type: boolean
+
 DOMIPCEnabled:
   description: >
     Set to 1 when a tab is running in a content process