client_wrapper: merge common/client_wrapper (sony#361)

Merged the latest source files from flutter/engine repo.

* src/flutter/shell/platform/common/client_wrapper/include/flutter/encodable_value.h
=> flutter/engine@a3c5a31

* src/flutter/shell/platform/common/client_wrapper/include/flutter/event_channel.h
src/flutter/shell/platform/common/client_wrapper/include/flutter/event_stream_handler.h
=> flutter/engine@52574ef

* src/flutter/shell/platform/common/client_wrapper/include/flutter/method_channel.h
=> flutter/engine@4165d4b

* src/flutter/shell/platform/common/client_wrapper/include/flutter/plugin_registrar.h
=> flutter/engine@6d263ea

* src/flutter/shell/platform/common/client_wrapper/standard_codec.cc
=> flutter/engine@71ee5f1

Signed-off-by: Hidenori Matsubayashi <[email protected]>

Author: HidenoriMatsubayashi

src/flutter/shell/platform/common/client_wrapper/include/flutter/encodable_value.h

@@ -215,6 +215,13 @@ class EncodableValue : public internal::EncodableValueVariant {
     }
     return std::get<int64_t>(*this);
   }
+
+  // Explicitly provide operator<, delegating to std::variant's operator<.
+  // There are issues with with the way the standard library-provided
+  // < and <=> comparisons interact with classes derived from variant.
+  friend bool operator<(const EncodableValue& lhs, const EncodableValue& rhs) {
+    return static_cast<const super&>(lhs) < static_cast<const super&>(rhs);
+  }
 };
 
 }  // namespace flutter

src/flutter/shell/platform/common/client_wrapper/include/flutter/event_channel.h

@@ -106,7 +106,7 @@ class EventChannel {
             if (error) {
               result = codec->EncodeErrorEnvelope(error->error_code,
                                                   error->error_message,
-                                                  error->error_details);
+                                                  error->error_details.get());
             } else {
               result = codec->EncodeSuccessEnvelope();
             }
@@ -119,7 +119,7 @@ class EventChannel {
               if (error) {
                 result = codec->EncodeErrorEnvelope(error->error_code,
                                                     error->error_message,
-                                                    error->error_details);
+                                                    error->error_details.get());
               } else {
                 result = codec->EncodeSuccessEnvelope();
               }

src/flutter/shell/platform/common/client_wrapper/include/flutter/event_stream_handler.h

@@ -5,6 +5,9 @@
 #ifndef FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_EVENT_STREAM_HANDLER_H_
 #define FLUTTER_SHELL_PLATFORM_COMMON_CLIENT_WRAPPER_INCLUDE_FLUTTER_EVENT_STREAM_HANDLER_H_
 
+#include <memory>
+#include <string>
+
 #include "event_sink.h"
 
 namespace flutter {
@@ -13,16 +16,16 @@ class EncodableValue;
 
 template <typename T = EncodableValue>
 struct StreamHandlerError {
-  const std::string& error_code;
-  const std::string& error_message;
-  const T* error_details;
+  const std::string error_code;
+  const std::string error_message;
+  const std::unique_ptr<T> error_details;
 
-  StreamHandlerError(const std::string& error_code,
-                     const std::string& error_message,
-                     const T* error_details)
+  StreamHandlerError(const std::string error_code,
+                     const std::string error_message,
+                     std::unique_ptr<T>&& error_details)
       : error_code(error_code),
         error_message(error_message),
-        error_details(error_details) {}
+        error_details(std::move(error_details)) {}
 };
 
 // Handler for stream setup and teardown requests.

src/flutter/shell/platform/common/client_wrapper/include/flutter/method_channel.h

@@ -91,9 +91,10 @@ class MethodChannel {
   // Registers a handler that should be called any time a method call is
   // received on this channel. A null handler will remove any previous handler.
   //
-  // Note that the MethodChannel does not own the handler, and will not
-  // unregister it on destruction, so the caller is responsible for
-  // unregistering explicitly if it should no longer be called.
+  // The handler will be owned by the underlying BinaryMessageHandler.
+  // Destroying the MethodChannel will not unregister the handler, so
+  // the caller is responsible for unregistering explicitly if the handler
+  // stops being valid before the engine is destroyed.
   void SetMethodCallHandler(MethodCallHandler<T> handler) const {
     if (!handler) {
       messenger_->SetMessageHandler(name_, nullptr);

src/flutter/shell/platform/common/client_wrapper/include/flutter/plugin_registrar.h

@@ -49,8 +49,8 @@ class PluginRegistrar {
   // Takes ownership of |plugin|.
   //
   // Plugins are not required to call this method if they have other lifetime
-  // management, but this is a convient place for plugins to be owned to ensure
-  // that they stay valid for any registered callbacks.
+  // management, but this is a convenient place for plugins to be owned to
+  // ensure that they stay valid for any registered callbacks.
   void AddPlugin(std::unique_ptr<Plugin> plugin);
 
  protected:

src/flutter/shell/platform/common/client_wrapper/standard_codec.cc

@@ -98,7 +98,7 @@ EncodableValue StandardCodecSerializer::ReadValue(
 void StandardCodecSerializer::WriteValue(const EncodableValue& value,
                                          ByteStreamWriter* stream) const {
   stream->WriteByte(static_cast<uint8_t>(EncodedTypeForValue(value)));
-  // TODO: Consider replacing this this with a std::visitor.
+  // TODO(cbracken): Consider replacing this with std::visit.
   switch (value.index()) {
     case 0:
     case 1: