Overhaul RenderNode's DisplayList management

* Move mValid to native
* Have destroyHardwareResources destroy everything
* Remove flaky mParentCount checks in setStaging
* All tree updates have an internal observer to
  ensure onRemovedFromTree() is a reliable signal
* onRemovedFromTree() immediately releases resources
  to avoid displaylist "leaks"

Test: Unit tests for validity added & pass, manually
verified that b/34072929 doesn't repro

Bug: 34072929

Change-Id: I856534b4ed1b7f009fc4b7cd13209b97fa42a71c
diff --git a/libs/hwui/renderthread/RenderProxy.cpp b/libs/hwui/renderthread/RenderProxy.cpp
index 022e871..fb79272 100644
--- a/libs/hwui/renderthread/RenderProxy.cpp
+++ b/libs/hwui/renderthread/RenderProxy.cpp
@@ -230,19 +230,18 @@
     return mDrawFrameTask.frameInfo();
 }
 
-int RenderProxy::syncAndDrawFrame(TreeObserver* observer) {
-    return mDrawFrameTask.drawFrame(observer);
+int RenderProxy::syncAndDrawFrame() {
+    return mDrawFrameTask.drawFrame();
 }
 
-CREATE_BRIDGE2(destroy, CanvasContext* context, TreeObserver* observer) {
-    args->context->destroy(args->observer);
+CREATE_BRIDGE1(destroy, CanvasContext* context) {
+    args->context->destroy();
     return nullptr;
 }
 
-void RenderProxy::destroy(TreeObserver* observer) {
+void RenderProxy::destroy() {
     SETUP_TASK(destroy);
     args->context = mContext;
-    args->observer = observer;
     // destroyCanvasAndSurface() needs a fence as when it returns the
     // underlying BufferQueue is going to be released from under
     // the render thread.
@@ -282,16 +281,15 @@
     return layer;
 }
 
-CREATE_BRIDGE3(buildLayer, CanvasContext* context, RenderNode* node, TreeObserver* observer) {
-    args->context->buildLayer(args->node, args->observer);
+CREATE_BRIDGE2(buildLayer, CanvasContext* context, RenderNode* node) {
+    args->context->buildLayer(args->node);
     return nullptr;
 }
 
-void RenderProxy::buildLayer(RenderNode* node, TreeObserver* observer) {
+void RenderProxy::buildLayer(RenderNode* node) {
     SETUP_TASK(buildLayer);
     args->context = mContext;
     args->node = node;
-    args->observer = observer;
     postAndWait(task);
 }
 
@@ -328,15 +326,14 @@
     postAndWait(task);
 }
 
-CREATE_BRIDGE2(destroyHardwareResources, CanvasContext* context, TreeObserver* observer) {
-    args->context->destroyHardwareResources(args->observer);
+CREATE_BRIDGE1(destroyHardwareResources, CanvasContext* context) {
+    args->context->destroyHardwareResources();
     return nullptr;
 }
 
-void RenderProxy::destroyHardwareResources(TreeObserver* observer) {
+void RenderProxy::destroyHardwareResources() {
     SETUP_TASK(destroyHardwareResources);
     args->context = mContext;
-    args->observer = observer;
     postAndWait(task);
 }