Desktop: fix memory leak after recomposition, when composition is dis…

…posed.

Fixes JetBrains/compose-multiplatform#538 and https://partnerissuetracker.corp.google.com/issues/170869626#comment4

As far as I figure out how observation works, it is enough to call `clearInvalidObservations` in the end of the every frame.
Because all changes will be commited before (on recomposition/layout/draw).
Similar code is in https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/ui/ui/src/androidMain/kotlin/androidx/compose/ui/platform/AndroidComposeView.android.kt;l=378;drc=f3b4f4f28cf61d4434af59d9247a9d2f6d5d70e7.

Bug: 183493610
Test: JetBrains/compose-multiplatform#538 (comment), click "Next" multiple times, run VisualVM, run GC, dump heap, find "Presenter"
Test: ./gradlew jvmTest desktopTest -Pandroidx.compose.multiplatformEnabled=true
Change-Id:  I864f4e7aeca28547465ea468229e19426d7b2827

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/platform/DesktopOwner.desktop.kt

@@ -19,7 +19,6 @@
 package androidx.compose.ui.platform
 
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.key
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.ExperimentalComposeUiApi
@@ -191,6 +190,7 @@ internal class DesktopOwner(
     override fun onDetach(node: LayoutNode) {
         measureAndLayoutDelegate.onNodeDetached(node)
         snapshotObserver.clear(node)
+        needClearObservations = true
     }
 
     override val measureIteration: Long get() = measureAndLayoutDelegate.measureIteration
@@ -207,6 +207,16 @@ internal class DesktopOwner(
         measureAndLayout()
         needsDraw = false
         draw(canvas)
+        clearInvalidObservations()
+    }
+
+    private var needClearObservations = false
+
+    private fun clearInvalidObservations() {
+        if (needClearObservations) {
+            snapshotObserver.clearInvalidObservations()
+            needClearObservations = false
+        }
     }
 
     private fun requestLayout() {
@@ -248,7 +258,8 @@ internal class DesktopOwner(
             invalidateParentLayer()
             requestDraw()
         },
-        drawBlock = drawBlock
+        drawBlock = drawBlock,
+        onDestroy = { needClearObservations = true }
     )
 
     override fun onSemanticsChange() = Unit

compose/ui/ui/src/desktopMain/kotlin/androidx/compose/ui/platform/SkijaLayer.desktop.kt

@@ -47,7 +47,8 @@ import org.jetbrains.skija.ShadowUtils
 internal class SkijaLayer(
     private val getDensity: () -> Density,
     private val invalidateParentLayer: () -> Unit,
-    private val drawBlock: (Canvas) -> Unit
+    private val drawBlock: (Canvas) -> Unit,
+    private val onDestroy: () -> Unit = {}
 ) : OwnedLayer {
     private var size = IntSize.Zero
     private var position = IntOffset.Zero
@@ -76,6 +77,7 @@ internal class SkijaLayer(
         picture?.close()
         pictureRecorder.close()
         isDestroyed = true
+        onDestroy()
     }
 
     override fun resize(size: IntSize) {