For #21296: add ProfilerMarkers.addForDispatchTouchEvent.

app/src/main/java/org/mozilla/fenix/HomeActivity.kt

@@ -19,6 +19,7 @@ import android.view.KeyEvent
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ActionMode
+import android.view.MotionEvent
 import android.view.ViewConfiguration
 import android.view.WindowManager.LayoutParams.FLAG_SECURE
 import androidx.annotation.CallSuper
@@ -581,6 +582,11 @@ open class HomeActivity : LocaleAwareAppCompatActivity(), NavHostActivity {
         return false
     }
 
+    override fun dispatchTouchEvent(ev: MotionEvent?): Boolean {
+        ProfilerMarkers.addForDispatchTouchEvent(components.core.engine.profiler, ev)
+        return super.dispatchTouchEvent(ev)
+    }
+
     final override fun onKeyDown(keyCode: Int, event: KeyEvent?): Boolean {
         // Inspired by https://searchfox.org/mozilla-esr68/source/mobile/android/base/java/org/mozilla/gecko/BrowserApp.java#584-613
         // Android N and Huawei devices have broken onKeyLongPress events for the back button, so we

app/src/main/java/org/mozilla/fenix/perf/ProfilerMarkers.kt

@@ -5,6 +5,7 @@
 package org.mozilla.fenix.perf
 
 import android.app.Activity
+import android.view.MotionEvent
 import android.view.View
 import android.view.ViewTreeObserver
 import androidx.core.view.doOnPreDraw
@@ -28,6 +29,20 @@ object ProfilerMarkers {
             profiler?.addMarker("onPreDraw", "expected first frame via HomeActivity.onStart")
         }
     }
+
+    fun addForDispatchTouchEvent(profiler: Profiler?, ev: MotionEvent?) {
+        // We only run this if the profiler is active to minimize any possible delay on touch events.
+        if (profiler?.isProfilerActive() == true) {
+            // We only do this subset because 1) other actions like MOVE may be spammy and 2) doing
+            // a generic ev?.action::class.simpleName may be too expensive for dispatchTouchEvent.
+            val detailText = when (ev?.action) {
+                MotionEvent.ACTION_DOWN -> "ACTION_DOWN"
+                MotionEvent.ACTION_UP -> "ACTION_UP"
+                else -> return
+            }
+            profiler.addMarker("dispatchTouchEvent", detailText)
+        }
+    }
 }
 
 /**