Avoid use of shared_from_this in StateTarget

Summary:
`StateTarget` no longer uses `shared_from_this`, this allows us to remove need for `enable_shared_from_this`

I decided to put `state->commit` call inside `ShadowTree.cpp` because I needed to have access to `shared_ptr` of shadow node from outside of the class itself.
`state->commit` was originally designed to be only called by `ShadowNode` but this does not seem to be the case anymore since it is called from `UIManager` as well.

changelog: [internal]

Reviewed By: shergin

Differential Revision: D18032532

fbshipit-source-id: 75c874fd04f86adc07bfddbef3a0384e17c2067b

ReactCommon/fabric/core/shadownode/ShadowNode.cpp

@@ -224,9 +224,6 @@ void ShadowNode::cloneChildrenIfShared() {
 
 void ShadowNode::setMounted(bool mounted) const {
   family_->eventEmitter_->setEnabled(mounted);
-  if (mounted && state_) {
-    state_->commit(*this);
-  }
 }
 
 AncestorList ShadowNode::getAncestors(

ReactCommon/fabric/core/shadownode/ShadowNode.h

@@ -40,8 +40,7 @@ using SharedShadowNodeSharedList = std::shared_ptr<const SharedShadowNodeList>;
 using SharedShadowNodeUnsharedList = std::shared_ptr<SharedShadowNodeList>;
 
 class ShadowNode : public virtual Sealable,
-                   public virtual DebugStringConvertible,
-                   public std::enable_shared_from_this<ShadowNode> {
+                   public virtual DebugStringConvertible {
  public:
   using Shared = std::shared_ptr<ShadowNode const>;
   using Weak = std::weak_ptr<ShadowNode const>;

ReactCommon/fabric/core/state/State.cpp

@@ -26,7 +26,7 @@ State::State(State const &state) : stateCoordinator_(state.stateCoordinator_){};
 State::State(StateCoordinator::Shared const &stateCoordinator)
     : stateCoordinator_(stateCoordinator){};
 
-void State::commit(const ShadowNode &shadowNode) const {
+void State::commit(std::shared_ptr<ShadowNode const> const &shadowNode) const {
   stateCoordinator_->setTarget(StateTarget{shadowNode});
 }
 

ReactCommon/fabric/core/state/State.h

@@ -40,18 +40,13 @@ class State {
   virtual void updateState(folly::dynamic data) const;
 #endif
 
+  void commit(std::shared_ptr<ShadowNode const> const &shadowNode) const;
+
  protected:
   StateCoordinator::Shared stateCoordinator_;
 
  private:
-  friend class ShadowNode;
   friend class StateCoordinator;
-  friend class UIManager;
-
-  /*
-   * Must be used by `ShadowNode` *only*.
-   */
-  void commit(const ShadowNode &shadowNode) const;
 
   /*
    * Indicates that the state was committed once and then was replaced by a

ReactCommon/fabric/core/state/StateTarget.cpp

@@ -13,8 +13,8 @@ namespace react {
 
 StateTarget::StateTarget() : shadowNode_(nullptr) {}
 
-StateTarget::StateTarget(const ShadowNode &shadowNode)
-    : shadowNode_(shadowNode.shared_from_this()) {}
+StateTarget::StateTarget(std::shared_ptr<ShadowNode const> shadowNode)
+    : shadowNode_(shadowNode) {}
 
 StateTarget::operator bool() const {
   return (bool)shadowNode_;

ReactCommon/fabric/core/state/StateTarget.h

@@ -29,7 +29,7 @@ class StateTarget {
   /*
    * Creates a target which points to a given `ShadowNode`.
    */
-  explicit StateTarget(const ShadowNode &shadowNode);
+  explicit StateTarget(std::shared_ptr<ShadowNode const> shadowNode);
 
   /*
    * Copyable and moveable.

ReactCommon/fabric/mounting/ShadowTree.cpp

@@ -21,6 +21,13 @@
 namespace facebook {
 namespace react {
 
+static void CommitState(ShadowNode::Shared const &shadowNode) {
+  auto state = shadowNode->getState();
+  if (state) {
+    state->commit(shadowNode);
+  }
+}
+
 static void updateMountedFlag(
     const SharedShadowNodeList &oldChildren,
     const SharedShadowNodeList &newChildren) {
@@ -58,6 +65,7 @@ static void updateMountedFlag(
     }
 
     newChild->setMounted(true);
+    CommitState(newChild);
     oldChild->setMounted(false);
 
     updateMountedFlag(oldChild->getChildren(), newChild->getChildren());
@@ -69,6 +77,7 @@ static void updateMountedFlag(
   for (index = lastIndexAfterFirstStage; index < newChildren.size(); index++) {
     const auto &newChild = newChildren[index];
     newChild->setMounted(true);
+    CommitState(newChild);
     updateMountedFlag({}, newChild->getChildren());
   }
 

ReactCommon/fabric/uimanager/UIManager.cpp

@@ -57,7 +57,7 @@ SharedShadowNode UIManager::createNode(
   // explicitly associate the ShadowNode with the State here so that updateState
   // is always safe and effectful.
   if (state) {
-    state->commit(*shadowNode);
+    state->commit(shadowNode);
   }
 
   if (delegate_) {