Add CHECKs to investigate WebSocket crash.

Sometimes handshake_stream_ is null in PerformUpgrade(), causing a
crash.  These CHECKs will allow us to distinguish between the following
three possible causes:
  * OnHandshakeStreamCreated() has never been called;
  * OnHandshakeStreamCreated() has been called with nullptr;
  * PerformUpgrade() has already been called.

Bug: 842575
Change-Id: Idd0ff4fecdeadee2d8286363a3b81ca6246b709e
Reviewed-on: https://chromium-review.googlesource.com/1069191
Commit-Queue: Adam Rice <ricea@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560952}

net/websockets/websocket_stream.cc

@@ -114,7 +114,9 @@ class WebSocketStreamRequestImpl : public WebSocketStreamRequest {
                                             delegate_.get(),
                                             kTrafficAnnotation)),
         connect_delegate_(std::move(connect_delegate)),
-        handshake_stream_(nullptr) {
+        handshake_stream_(nullptr),
+        on_handshake_stream_created_has_been_called_(false),
+        perform_upgrade_has_been_called_(false) {
     create_helper->set_stream_request(this);
     HttpRequestHeaders headers = additional_headers;
     headers.SetHeader(websockets::kUpgrade, websockets::kWebSocketLowercase);
@@ -156,6 +158,11 @@ class WebSocketStreamRequestImpl : public WebSocketStreamRequest {
 
   void OnHandshakeStreamCreated(
       WebSocketHandshakeStreamBase* handshake_stream) override {
+    // TODO(bnc): Change to DCHECK after https://crbug.com/842575 is fixed.
+    CHECK(handshake_stream);
+
+    on_handshake_stream_created_has_been_called_ = true;
+
     handshake_stream_ = handshake_stream;
   }
 
@@ -176,10 +183,14 @@ class WebSocketStreamRequestImpl : public WebSocketStreamRequest {
 
   void PerformUpgrade() {
     DCHECK(timer_);
+    CHECK(!perform_upgrade_has_been_called_);
+    CHECK(on_handshake_stream_created_has_been_called_);
     // TODO(bnc): Change to DCHECK after https://crbug.com/842575 is fixed.
     CHECK(handshake_stream_);
     CHECK(connect_delegate_);
 
+    perform_upgrade_has_been_called_ = true;
+
     timer_->Stop();
 
     std::unique_ptr<URLRequest> url_request = std::move(url_request_);
@@ -266,6 +277,10 @@ class WebSocketStreamRequestImpl : public WebSocketStreamRequest {
   // succeeded.
   WebSocketHandshakeStreamBase* handshake_stream_;
 
+  // TODO(bnc): Remove after https://crbug.com/842575 is fixed.
+  bool on_handshake_stream_created_has_been_called_;
+  bool perform_upgrade_has_been_called_;
+
   // The failure message supplied by WebSocketBasicHandshakeStream, if any.
   std::string failure_message_;