Add android app start time implementation

Summary:
This diff adds the android `appStartTime` implementation for `ReactMarker`.

Changelog:
[Android][Internal] - Add the android `appStartTime` implementation for `ReactMarker`

Reviewed By: rshest

Differential Revision: D43523607

fbshipit-source-id: 9dc95db30e36e7c1bfb262c74598f0ac249522f2

ReactAndroid/src/main/java/com/facebook/react/bridge/ReactMarker.java

@@ -42,6 +42,9 @@ void logFabricMarker(
   private static final List<FabricMarkerListener> sFabricMarkerListeners =
       new CopyOnWriteArrayList<>();
 
+  // The android app start time that to be set by the corresponding app
+  private static long sAppStartTime;
+
   @DoNotStrip
   public static void addListener(MarkerListener listener) {
     if (!sListeners.contains(listener)) {
@@ -138,4 +141,14 @@ public static void logMarker(ReactMarkerConstants name, @Nullable String tag, in
       listener.logMarker(name, tag, instanceKey);
     }
   }
+
+  @DoNotStrip
+  public static void setAppStartTime(long appStartTime) {
+    sAppStartTime = appStartTime;
+  }
+
+  @DoNotStrip
+  public static double getAppStartTime() {
+    return (double) sAppStartTime;
+  }
 }

ReactAndroid/src/main/jni/react/jni/JReactMarker.cpp

@@ -20,6 +20,7 @@ void JReactMarker::setLogPerfMarkerIfNeeded() {
     ReactMarker::logTaggedMarkerImpl = JReactMarker::logPerfMarker;
     ReactMarker::logTaggedMarkerBridgelessImpl =
         JReactMarker::logPerfMarkerBridgeless;
+    ReactMarker::getAppStartTimeImpl = JReactMarker::getAppStartTime;
   });
 }
 
@@ -103,5 +104,11 @@ void JReactMarker::logPerfMarkerWithInstanceKey(
   }
 }
 
+double JReactMarker::getAppStartTime() {
+  static auto cls = javaClassStatic();
+  static auto meth = cls->getStaticMethod<double()>("getAppStartTime");
+  return meth(cls);
+}
+
 } // namespace react
 } // namespace facebook

ReactAndroid/src/main/jni/react/jni/JReactMarker.h

@@ -38,6 +38,7 @@ class JReactMarker : public facebook::jni::JavaClass<JReactMarker> {
       const ReactMarker::ReactMarkerId markerId,
       const char *tag,
       const int instanceKey);
+  static double getAppStartTime();
 };
 
 } // namespace react