[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/protocol/page_handler.h

 // 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.
 
 #ifndef CONTENT_BROWSER_DEVTOOLS_PROTOCOL_PAGE_HANDLER_H_
 #define CONTENT_BROWSER_DEVTOOLS_PROTOCOL_PAGE_HANDLER_H_
 
 #include <stddef.h>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "cc/output/compositor_frame_metadata.h"
+#include "content/browser/devtools/protocol/devtools_domain_handler.h"
 #include "content/browser/devtools/protocol/page.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/readback_types.h"
 
 class SkBitmap;
 
 namespace content {
 
 class NavigationHandle;
 class PageNavigationThrottle;
 class RenderFrameHostImpl;
 class WebContentsImpl;
 
 namespace protocol {
 
 class ColorPicker;
 
-class PageHandler : public Page::Backend,
+class PageHandler : public DevToolsDomainHandler,
+                    public Page::Backend,
                     public NotificationObserver {
  public:
   PageHandler();
   ~PageHandler() override;
 
-  void Wire(UberDispatcher*);
-  void SetRenderFrameHost(RenderFrameHostImpl* host);
+  void Wire(UberDispatcher* dispatcher) override;
+  void SetRenderFrameHost(RenderFrameHostImpl* host) override;
   void OnSwapCompositorFrame(cc::CompositorFrameMetadata frame_metadata);
   void OnSynchronousSwapCompositorFrame(
       cc::CompositorFrameMetadata frame_metadata);
   void DidAttachInterstitialPage();
   void DidDetachInterstitialPage();
   bool screencast_enabled() const { return enabled_ && screencast_enabled_; }
 
   Response Enable() override;
   Response Disable() override;
 
@@ skipping 84 matching lines @@
   NotificationRegistrar registrar_;
   base::WeakPtrFactory<PageHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PageHandler);
 };
 
 }  // namespace protocol
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_PROTOCOL_PAGE_HANDLER_H_