[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/protocol/io_handler.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/devtools/protocol/io_handler.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/bind.h"
 #include "base/files/file.h"
 #include "base/files/file_util.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/strings/string_number_conversions.h"
 #include "content/browser/devtools/devtools_io_context.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace content {
 namespace protocol {
 
 IOHandler::IOHandler(DevToolsIOContext* io_context)
-    : io_context_(io_context)
+    : DevToolsDomainHandler(IO::Metainfo::domainName),
+      io_context_(io_context)
     , weak_factory_(this) {}
 
 IOHandler::~IOHandler() {}
 
 void IOHandler::Wire(UberDispatcher* dispatcher) {
   frontend_.reset(new IO::Frontend(dispatcher->channel()));
   IO::Dispatcher::wire(dispatcher, this);
 }
 
-Response IOHandler::Disable() {
-  return Response::OK();
-}
-
 void IOHandler::Read(
     const std::string& handle,
     Maybe<int> offset,
     Maybe<int> max_size,
     std::unique_ptr<ReadCallback> callback) {
   static const size_t kDefaultChunkSize = 10 * 1024 * 1024;
 
   scoped_refptr<DevToolsIOContext::Stream> stream =
       io_context_->GetByHandle(handle);
   if (!stream) {
@@ skipping 18 matching lines @@
   callback->sendSuccess(data->data(), eof);
 }
 
 Response IOHandler::Close(const std::string& handle) {
   return io_context_->Close(handle) ? Response::OK()
       : Response::InvalidParams("Invalid stream handle");
 }
 
 }  // namespace protocol
 }  // namespace content