Bug 1357386: Gather telemetry for toplevel data: URI loads. r=dveditz,francois

docshell/base/nsDocShell.cpp

@@ -11018,6 +11018,28 @@ nsDocShell::DoURILoad(nsIURI* aURI,
       new LoadInfo(loadingPrincipal, aTriggeringPrincipal, loadingNode,
                    securityFlags, aContentPolicyType);
 
+  if (aContentPolicyType == nsIContentPolicy::TYPE_DOCUMENT) {
+    enum TopLevelDataState {
+      DATA_NAVIGATED = 0,
+      DATA_TYPED = 1,
+      NO_DATA = 2,
+    };
+    bool isDataURI = (NS_SUCCEEDED(aURI->SchemeIs("data", &isDataURI)) && isDataURI);
+    if (isDataURI) {
+      // In all cases where the toplevel document is navigated to a data: URI
+      // the triggeringPrincipal is a CodeBasePrincipal. In all other cases
+      // e.g. typing a data: URL into the URL-Bar or also clicking a bookmark 
+      // uses a SystemPrincipal as the triggeringPrincipal.
+      if (aTriggeringPrincipal->GetIsCodebasePrincipal()) {
+        Telemetry::Accumulate(Telemetry::DOCUMENT_DATA_URI_LOADS, DATA_NAVIGATED);
+      } else {
+        Telemetry::Accumulate(Telemetry::DOCUMENT_DATA_URI_LOADS, DATA_TYPED);
+      }
+    } else {
+      Telemetry::Accumulate(Telemetry::DOCUMENT_DATA_URI_LOADS, NO_DATA);
+    }
+  }
+
   if (aPrincipalToInherit) {
     loadInfo->SetPrincipalToInherit(aPrincipalToInherit);
   }

toolkit/components/telemetry/Histograms.json

@@ -13173,6 +13173,15 @@
     "bug_numbers": [1351021],
     "description": "Every time we run an unlabeled runnable, this histogram records the time (in ms) since the last unlabeled runnable ran."
   },
+  "DOCUMENT_DATA_URI_LOADS": {
+    "record_in_processes": ["main", "content"],
+    "alert_emails": ["seceng-telemetry@mozilla.com"],
+    "bug_numbers": [1357386],
+    "expires_in_version": "60",
+    "kind": "enumerated",
+    "n_values": 3,
+    "description": "Whether a toplevel document uses data: URI? (0=data-navigated, 1=data-typed, 2=nodata)"
+  },
   "VFC_INVALIDATE_LOCK_WAIT_MS": {
     "record_in_processes": ["main", "content"],
     "alert_emails": ["jwwang@mozilla.com"],