Wait for full display in startup benchmarks

Change-Id: Iadd71fe9481d91620e7676dd0be318a1cbe9b4ba

benchmark/src/main/java/com/google/samples/apps/nowinandroid/startup/StartupBenchmark.kt

@@ -27,6 +27,7 @@ import androidx.benchmark.macro.StartupTimingMetric
 import androidx.benchmark.macro.junit4.MacrobenchmarkRule
 import androidx.test.internal.runner.junit4.AndroidJUnit4ClassRunner
 import com.google.samples.apps.nowinandroid.PACKAGE_NAME
+import com.google.samples.apps.nowinandroid.foryou.forYouWaitForContent
 import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
@@ -85,5 +86,7 @@ abstract class AbstractStartupBenchmark(private val startupMode: StartupMode) {
         }
     ) {
         startActivityAndWait()
+        // Waits until the content is ready to capture Time To Full Display 
+        forYouWaitForContent()
     }
 }