Fabric: ContextContainer is now able to store any copyable values

Summary:
@public
Previously, ContextContainer could store only `shared_ptr`s, but now it wraps all values in own `shared_ptr` container.
I wish we can use `unique_ptr` here, but apparently we cannot because `unique_ptr` does not support type-erasure (`std::unique_ptr<void>` is illigal).
Becasue ContextContainer is not supposed to be used in hot paths, the performance aspect of that does not actually matter.

Reviewed By: mdvacca

Differential Revision: D8853446

fbshipit-source-id: e5d0a5595fe44c59f1395d6ffccf9d3fed923c83

Author: shergin

ReactCommon/fabric/components/image/ImageComponentDescriptor.h

@@ -24,7 +24,7 @@ class ImageComponentDescriptor final:
 public:
   ImageComponentDescriptor(SharedEventDispatcher eventDispatcher, const SharedContextContainer &contextContainer):
     ConcreteComponentDescriptor(eventDispatcher),
-    imageManager_(contextContainer->getInstance<ImageManager>()) {}
+    imageManager_(contextContainer->getInstance<SharedImageManager>()) {}
 
   void adopt(UnsharedShadowNode shadowNode) const override {
     ConcreteComponentDescriptor::adopt(shadowNode);

ReactCommon/fabric/uimanager/ContextContainer.h

@@ -20,6 +20,7 @@ using SharedContextContainer = std::shared_ptr<ContextContainer>;
 
 /*
  * General purpose dependecy injection container.
+ * Instance types must be copyable.
  */
 class ContextContainer final {
 
@@ -30,11 +31,12 @@ class ContextContainer final {
    * by `{type, key}` pair.
    */
   template<typename T>
-  void registerInstance(std::shared_ptr<T> instance, const std::string &key = "") {
+  void registerInstance(const T &instance, const std::string &key = "") {
     std::lock_guard<std::mutex> lock(mutex_);
+
     instances_.insert({
       {std::type_index(typeid(T)), key},
-      instance
+      std::make_shared<T>(instance)
     });
   }
 
@@ -44,9 +46,10 @@ class ContextContainer final {
    * by {type, key} pair.
    */
   template<typename T>
-  std::shared_ptr<T> getInstance(const std::string &key = "") const {
+  T getInstance(const std::string &key = "") const {
     std::lock_guard<std::mutex> lock(mutex_);
-    return std::static_pointer_cast<T>(instances_.at({std::type_index(typeid(T)), key}));
+
+    return *std::static_pointer_cast<T>(instances_.at({std::type_index(typeid(T)), key}));
   }
 
 private: