Add onReactBridgeInitialized to Java native modules

This native module callback will be called on the JS thread after a ReactBridge instance has been created, but before the JS bundle is loaded. This allows for advanced native modules to add custom functionality (that isn't possible with the existing APIs) into the context that will be available when the JS bundle loads.

ReactAndroid/src/main/java/com/facebook/react/bridge/BaseJavaModule.java

@@ -332,6 +332,11 @@ public boolean canOverrideExistingModule() {
     return false;
   }
 
+  @Override
+  public void onReactBridgeInitialized(ReactBridge bridge) {
+    // do nothing
+  }
+
   @Override
   public void onCatalystInstanceDestroy() {
     // do nothing

ReactAndroid/src/main/java/com/facebook/react/bridge/CatalystInstanceImpl.java

@@ -127,6 +127,7 @@ private ReactBridge initializeBridge(
       Systrace.endSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE);
     }
 
+    mJavaRegistry.notifyReactBridgeInitialized(bridge);
     return bridge;
   }
 

ReactAndroid/src/main/java/com/facebook/react/bridge/NativeModule.java

@@ -59,6 +59,15 @@ interface NativeMethod {
    */
   boolean canOverrideExistingModule();
 
+  /**
+   * Called on the JS thread after a ReactBridge has been created. This is useful for native modules
+   * that need to do any setup before the JS bundle has been loaded. An example of this would be
+   * installing custom functionality into the JavaScriptCore context.
+   *
+   * @param bridge the ReactBridge instance that has just been created
+   */
+  void onReactBridgeInitialized(ReactBridge bridge);
+
   /**
    * Called before {CatalystInstance#onHostDestroy}
    */

ReactAndroid/src/main/java/com/facebook/react/bridge/NativeModuleRegistry.java

@@ -114,6 +114,19 @@ private NativeModuleRegistry(
     }
   }
 
+  /* package */ void notifyReactBridgeInitialized(ReactBridge bridge) {
+    Systrace.beginSection(
+        Systrace.TRACE_TAG_REACT_JAVA_BRIDGE,
+        "NativeModuleRegistry_notifyReactBridgeInitialized");
+    try {
+      for (NativeModule nativeModule : mModuleInstances.values()) {
+        nativeModule.onReactBridgeInitialized(bridge);
+      }
+    } finally {
+      Systrace.endSection(Systrace.TRACE_TAG_REACT_JAVA_BRIDGE);
+    }
+  }
+
   public void onBatchComplete() {
     for (int i = 0; i < mBatchCompleteListenerModules.size(); i++) {
       mBatchCompleteListenerModules.get(i).onBatchComplete();