For #22177: change onMeasure/onLayout markers into a single track + draw.

When you want to look at one of these markers, you usually want to look
at all three so I found that having them on a single track was easier to
follow. Since they run in sequence, they should never overlap and that
should minimize confusion.

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

@@ -213,7 +213,6 @@ open class HomeActivity : LocaleAwareAppCompatActivity(), NavHostActivity {
 
         binding = ActivityHomeBinding.inflate(layoutInflater)
         setContentView(binding.root)
-        binding.root.profilerProvider = { components.core.engine.profiler }
         ProfilerMarkers.addListenerForOnGlobalLayout(components.core.engine, this, binding.root)
 
         // Must be after we set the content view

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

@@ -5,12 +5,14 @@
 package org.mozilla.fenix.perf
 
 import android.content.Context
+import android.graphics.Canvas
 import android.util.AttributeSet
 import android.widget.LinearLayout
 import mozilla.components.concept.base.profiler.Profiler
 import org.mozilla.fenix.HomeActivity
+import org.mozilla.fenix.ext.components
 
-private const val DETAIL_TEXT = "RootLinearLayout"
+private const val MARKER_NAME = "Measure, Layout, Draw"
 
 /**
  * A [LinearLayout] that adds profiler markers for various methods. This is intended to be used on
@@ -18,17 +20,25 @@ private const val DETAIL_TEXT = "RootLinearLayout"
  */
 class HomeActivityRootLinearLayout(context: Context, attrs: AttributeSet) : LinearLayout(context, attrs) {
 
-    var profilerProvider: () -> Profiler? = { null }
+    private val profiler: Profiler? = context.components.core.engine.profiler
 
     override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
-        val profilerStartTime = profilerProvider.invoke()?.getProfilerTime()
+        val profilerStartTime = profiler?.getProfilerTime()
         super.onMeasure(widthMeasureSpec, heightMeasureSpec)
-        profilerProvider.invoke()?.addMarker("onMeasure", profilerStartTime, DETAIL_TEXT)
+        profiler?.addMarker(MARKER_NAME, profilerStartTime, "onMeasure (HomeActivity root)")
     }
 
     override fun onLayout(changed: Boolean, l: Int, t: Int, r: Int, b: Int) {
-        val profilerStartTime = profilerProvider.invoke()?.getProfilerTime()
+        val profilerStartTime = profiler?.getProfilerTime()
         super.onLayout(changed, l, t, r, b)
-        profilerProvider.invoke()?.addMarker("onLayout", profilerStartTime, DETAIL_TEXT)
+        profiler?.addMarker(MARKER_NAME, profilerStartTime, "onLayout (HomeActivity root)")
+    }
+
+    override fun dispatchDraw(canvas: Canvas?) {
+        // We instrument dispatchDraw, for drawing children, because LinearLayout never draws itself,
+        // i.e. it never calls onDraw or draw.
+        val profilerStartTime = profiler?.getProfilerTime()
+        super.dispatchDraw(canvas)
+        profiler?.addMarker(MARKER_NAME, profilerStartTime, "dispatchDraw (HomeActivity root)")
     }
 }