[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/protocol/input_handler.cc

 // Copyright 2014 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/input_handler.h"
 
 #include <stddef.h>
 
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/output/compositor_frame_metadata.h"
+#include "content/browser/devtools/devtools_session.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/common/input/synthetic_pinch_gesture_params.h"
 #include "content/common/input/synthetic_smooth_scroll_gesture_params.h"
 #include "content/common/input/synthetic_tap_gesture_params.h"
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "ui/events/keycodes/dom/keycode_converter.h"
 #include "ui/gfx/geometry/point.h"
 
 namespace content {
@@ skipping 149 matching lines @@
     callback->sendSuccess();
   } else {
     callback->sendFailure(Response::Error(
         base::StringPrintf("Synthetic scroll failed, result was %d", result)));
   }
 }
 
 }  // namespace
 
 InputHandler::InputHandler()
-    : host_(NULL),
+    : DevToolsDomainHandler(Input::Metainfo::domainName),
+      host_(nullptr),
       page_scale_factor_(1.0),
       last_id_(0),
       weak_factory_(this) {
 }
 
 InputHandler::~InputHandler() {
 }
 
+// static
+InputHandler* InputHandler::FromSession(DevToolsSession* session) {
+  return static_cast<InputHandler*>(
+      session->GetHandlerByName(Input::Metainfo::domainName));
+}
+
 void InputHandler::SetRenderFrameHost(RenderFrameHostImpl* host) {
   host_ = host;
 }
 
 void InputHandler::Wire(UberDispatcher* dispatcher) {
   Input::Dispatcher::wire(dispatcher, this);
 }
 
 void InputHandler::OnSwapCompositorFrame(
     const cc::CompositorFrameMetadata& frame_metadata) {
@@ skipping 331 matching lines @@
   for (int i = 0; i < count; i++) {
     host_->GetRenderWidgetHost()->QueueSyntheticGesture(
         SyntheticGesture::Create(gesture_params),
         base::Bind(&TapGestureResponse::OnGestureResult,
                    base::Unretained(response)));
   }
 }
 
 }  // namespace protocol
 }  // namespace content