Add blob implementation with WebSocket integration

Summary:
This is the first PR from a series of PRs grabbou and me will make to add blob support to React Native. The next PR will include blob support for XMLHttpRequest.

I'd like to get this merged with minimal changes to preserve the attribution. My next PR can contain bigger changes.

Blobs are used to transfer binary data between server and client. Currently React Native lacks a way to deal with binary data. The only thing that comes close is uploading files through a URI.

Current workarounds to transfer binary data includes encoding and decoding them to base64 and and transferring them as string, which is not ideal, since it increases the payload size and the whole payload needs to be sent via the bridge every time changes are made.

The PR adds a way to deal with blobs via a new native module. The blob is constructed on the native side and the data never needs to pass through the bridge. Currently the only way to create a blob is to receive a blob from the server via websocket.

The PR is largely a direct port of https://github.com/silklabs/silk/tree/master/react-native-blobs by philikon into RN (with changes to integrate with RN), and attributed as such.

> **Note:** This is a breaking change for all people running iOS without CocoaPods. You will have to manually add `RCTBlob.xcodeproj` to your `Libraries` and then, add it to Build Phases. Just follow the process of manual linking. We'll also need to document this process in the release notes.

Related discussion - https://github.com/facebook/react-native/issues/11103

- `Image` can't show image when `URL.createObjectURL` is used with large images on Android

The websocket integration can be tested via a simple server,

```js
const fs = require('fs');
const http = require('http');

const WebSocketServer = require('ws').Server;

const wss = new WebSocketServer({
  server: http.createServer().listen(7232),
});

wss.on('connection', (ws) => {
  ws.on('message', (d) => {
    console.log(d);
  });

  ws.send(fs.readFileSync('./some-file'));
});
```

Then on the client,

```js
var ws = new WebSocket('ws://localhost:7232');

ws.binaryType = 'blob';

ws.onerror = (error) => {
  console.error(error);
};

ws.onmessage = (e) => {
  console.log(e.data);
  ws.send(e.data);
};
```

cc brentvatne ide
Closes https://github.com/facebook/react-native/pull/11417

Reviewed By: sahrens

Differential Revision: D5188484

Pulled By: javache

fbshipit-source-id: 6afcbc4d19aa7a27b0dc9d52701ba400e7d7e98f

Libraries/WebSocket/RCTWebSocketModule.m

@@ -36,11 +36,15 @@
 
 @implementation RCTWebSocketModule
 {
-    NSMutableDictionary<NSNumber *, RCTSRWebSocket *> *_sockets;
+  NSMutableDictionary<NSNumber *, RCTSRWebSocket *> *_sockets;
+  NSMutableDictionary<NSNumber *, id> *_contentHandlers;
 }
 
 RCT_EXPORT_MODULE()
 
+// Used by RCTBlobModule
+@synthesize methodQueue = _methodQueue;
+
 - (NSArray *)supportedEvents
 {
   return @[@"websocketMessage",
@@ -60,7 +64,7 @@ RCT_EXPORT_MODULE()
 RCT_EXPORT_METHOD(connect:(NSURL *)URL protocols:(NSArray *)protocols headers:(NSDictionary *)headers socketID:(nonnull NSNumber *)socketID)
 {
   NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
-  
+
   // We load cookies from sharedHTTPCookieStorage (shared with XHR and
   // fetch). To get secure cookies for wss URLs, replace wss with https
   // in the URL.
@@ -72,7 +76,7 @@ RCT_EXPORT_METHOD(connect:(NSURL *)URL protocols:(NSArray *)protocols headers:(N
   // Load and set the cookie header.
   NSArray<NSHTTPCookie *> *cookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:components.URL];
   request.allHTTPHeaderFields = [NSHTTPCookie requestHeaderFieldsWithCookies:cookies];
-  
+
   // Load supplied headers
   [headers enumerateKeysAndObjectsUsingBlock:^(NSString *key, id value, BOOL *stop) {
     [request addValue:[RCTConvert NSString:value] forHTTPHeaderField:key];
@@ -88,15 +92,19 @@ RCT_EXPORT_METHOD(connect:(NSURL *)URL protocols:(NSArray *)protocols headers:(N
   [webSocket open];
 }
 
-RCT_EXPORT_METHOD(send:(NSString *)message socketID:(nonnull NSNumber *)socketID)
+RCT_EXPORT_METHOD(send:(NSString *)message forSocketID:(nonnull NSNumber *)socketID)
 {
   [_sockets[socketID] send:message];
 }
 
-RCT_EXPORT_METHOD(sendBinary:(NSString *)base64String socketID:(nonnull NSNumber *)socketID)
+RCT_EXPORT_METHOD(sendBinary:(NSString *)base64String forSocketID:(nonnull NSNumber *)socketID)
 {
-  NSData *message = [[NSData alloc] initWithBase64EncodedString:base64String options:0];
-  [_sockets[socketID] send:message];
+  [self sendData:[[NSData alloc] initWithBase64EncodedString:base64String options:0] forSocketID:socketID];
+}
+
+- (void)sendData:(NSData *)data forSocketID:(nonnull NSNumber *)socketID
+{
+  [_sockets[socketID] send:data];
 }
 
 RCT_EXPORT_METHOD(ping:(nonnull NSNumber *)socketID)
@@ -110,14 +118,36 @@ RCT_EXPORT_METHOD(close:(nonnull NSNumber *)socketID)
   [_sockets removeObjectForKey:socketID];
 }
 
+- (void)setContentHandler:(id<RCTWebSocketContentHandler>)handler forSocketID:(NSString *)socketID
+{
+  if (!_contentHandlers) {
+    _contentHandlers = [NSMutableDictionary new];
+  }
+  _contentHandlers[socketID] = handler;
+}
+
 #pragma mark - RCTSRWebSocketDelegate methods
 
 - (void)webSocket:(RCTSRWebSocket *)webSocket didReceiveMessage:(id)message
 {
-  BOOL binary = [message isKindOfClass:[NSData class]];
+  NSString *type;
+
+  NSNumber *socketID = [webSocket reactTag];
+  id contentHandler = _contentHandlers[socketID];
+  if (contentHandler) {
+    message = [contentHandler processMessage:message forSocketID:socketID withType:&type];
+  } else {
+    if ([message isKindOfClass:[NSData class]]) {
+      type = @"binary";
+      message = [message base64EncodedStringWithOptions:0];
+    } else {
+      type = @"text";
+    }
+  }
+
   [self sendEventWithName:@"websocketMessage" body:@{
-    @"data": binary ? [message base64EncodedStringWithOptions:0] : message,
-    @"type": binary ? @"binary" : @"text",
+    @"data": message,
+    @"type": type,
     @"id": webSocket.reactTag
   }];
 }
@@ -131,21 +161,36 @@ RCT_EXPORT_METHOD(close:(nonnull NSNumber *)socketID)
 
 - (void)webSocket:(RCTSRWebSocket *)webSocket didFailWithError:(NSError *)error
 {
+  NSNumber *socketID = [webSocket reactTag];
+  _contentHandlers[socketID] = nil;
   [self sendEventWithName:@"websocketFailed" body:@{
-    @"message":error.localizedDescription,
-    @"id": webSocket.reactTag
+    @"message": error.localizedDescription,
+    @"id": socketID
   }];
 }
 
-- (void)webSocket:(RCTSRWebSocket *)webSocket didCloseWithCode:(NSInteger)code
-           reason:(NSString *)reason wasClean:(BOOL)wasClean
+- (void)webSocket:(RCTSRWebSocket *)webSocket
+ didCloseWithCode:(NSInteger)code
+           reason:(NSString *)reason
+         wasClean:(BOOL)wasClean
 {
+  NSNumber *socketID = [webSocket reactTag];
+  _contentHandlers[socketID] = nil;
   [self sendEventWithName:@"websocketClosed" body:@{
     @"code": @(code),
     @"reason": RCTNullIfNil(reason),
     @"clean": @(wasClean),
-    @"id": webSocket.reactTag
+    @"id": socketID
   }];
 }
 
 @end
+
+@implementation RCTBridge (RCTWebSocketModule)
+
+- (RCTWebSocketModule *)webSocketModule
+{
+  return [self moduleForClass:[RCTWebSocketModule class]];
+}
+
+@end