Bug 1694505 - Add an optional data path override to FOG init r=janerik

Differential Revision: https://phabricator.services.mozilla.com/D106192

toolkit/components/glean/gtest/TestFog.cpp

@@ -34,7 +34,8 @@ void GTest_FOG_ExpectFailure(const char* aMessage) {
 TEST(FOG, FogInitDoesntCrash)
 {
   Preferences::SetInt("telemetry.fog.test.localhost_port", -1);
-  ASSERT_EQ(NS_OK, fog_init());
+  const nsCString empty;
+  ASSERT_EQ(NS_OK, fog_init(&empty));
 }
 
 extern "C" void Rust_MeasureInitializeTime();

toolkit/components/glean/src/lib.rs

@@ -49,14 +49,18 @@ use crate::viaduct_uploader::ViaductUploader;
 /// This assembles client information and the Glean configuration and then initializes the global
 /// Glean instance.
 #[no_mangle]
-pub unsafe extern "C" fn fog_init() -> nsresult {
+pub unsafe extern "C" fn fog_init(data_path_override: &nsACString) -> nsresult {
     fog::metrics::fog::initialization.start();
 
     log::debug!("Initializing FOG.");
 
-    let data_path = match get_data_path() {
+    let data_path = if data_path_override.is_empty() {
+        match get_data_path() {
             Ok(dp) => dp,
             Err(e) => return e,
+        }
+    } else {
+        data_path_override.to_utf8().to_string()
     };
 
     let (app_build, app_display_version, channel) = match get_app_info() {

toolkit/components/glean/xpcom/FOG.cpp

@@ -31,7 +31,9 @@ already_AddRefed<FOG> FOG::GetSingleton() {
 void FOG::Shutdown() { glean::impl::fog_shutdown(); }
 
 NS_IMETHODIMP
-FOG::InitializeFOG() { return glean::impl::fog_init(); }
+FOG::InitializeFOG(const nsACString& aDataPathOverride) {
+  return glean::impl::fog_init(&aDataPathOverride);
+}
 
 NS_IMETHODIMP
 FOG::SetLogPings(bool aEnableLogPings) {

toolkit/components/glean/xpcom/nsIFOG.idl

@@ -14,8 +14,11 @@ interface nsIFOG : nsISupports
    *
    * To be scheduled at some opportune time after the bulk of Firefox startup
    * has completed.
+   *
+   * @param aDataPathOverride - The path of a custom Glean data path to use
+   *        instead of the profile dir.
    */
-  void initializeFOG();
+  void initializeFOG([optional] in AUTF8String aDataPathOverride);
 
   /**
    * Enable or Disable the logging of pings in the Glean SDK.