Bug 1922231 - Avoid recording to histograms or scalars in processes that don't match the probe definition, r=chutten.

Differential Revision: https://phabricator.services.mozilla.com/D224309

layout/style/PreferenceSheet.cpp

@@ -270,6 +270,11 @@ void PreferenceSheet::Initialize() {
     }
   }
 
+  // Telemetry for these preferences is only collected on the parent process.
+  if (!XRE_IsParentProcess()) {
+    return;
+  }
+
   nsAutoString useDocumentColorPref;
   switch (StaticPrefs::browser_display_document_color_use()) {
     case 1:

toolkit/components/startup/StartupTimeline.cpp

@@ -43,7 +43,11 @@ void StartupTimeline::RecordOnce(Event ev, const TimeStamp& aWhen) {
 
   Record(ev, aWhen);
 
-  // Record first paint timestamp as a scalar.
+  // Record first paint timestamp as a scalar in the parent process.
+  if (!XRE_IsParentProcess()) {
+    return;
+  }
+
   if (ev == FIRST_PAINT || ev == FIRST_PAINT2) {
     uint32_t firstPaintTime =
         (uint32_t)(aWhen - TimeStamp::ProcessCreation()).ToMilliseconds();

uriloader/preload/PreloaderBase.cpp

@@ -305,7 +305,7 @@ void PreloaderBase::CancelUsageTimer() {
 }
 
 void PreloaderBase::ReportUsageTelemetry() {
-  if (mUsageTelementryReported) {
+  if (mUsageTelementryReported || !XRE_IsContentProcess()) {
     return;
   }
   mUsageTelementryReported = true;