Register clipboard image blob in the browser process to copy data less.

third_party/WebKit/public/blink_headers.gypi

 # 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.
 
 {
   'variables': {
     'blink_public_sources': [
       "platform/callback/WebClosure.h",
       "platform/Platform.h",
       "platform/FilePathConversion.h",
@@ skipping 125 matching lines @@
       "platform/WebMediaStreamCenterClient.h",
       "platform/WebMediaStreamSource.h",
       "platform/WebMediaStreamTrack.h",
       "platform/WebMediaStreamTrackSourcesRequest.h",
       "platform/WebMemoryAllocatorDump.h",
       "platform/WebMemoryDumpProvider.h",
       "platform/WebMemoryPressureLevel.h",
       "platform/WebMessagePortChannel.h",
       "platform/WebMessagePortChannelClient.h",
       "platform/WebMimeRegistry.h",
+      "platform/WebMockClipboard.h",
       "platform/WebNativeScrollBehavior.h",
       "platform/WebNonCopyable.h",
       "platform/WebPageVisibilityState.h",
       "platform/WebPasswordCredential.h",
       "platform/WebPlatformEventListener.h",
       "platform/WebPlatformEventType.h",
       "platform/WebPluginListBuilder.h",
       "platform/WebPoint.h",
       "platform/WebPrerender.h",
       "platform/WebPrerenderingSupport.h",
@@ skipping 343 matching lines @@
       "web/modules/serviceworker/WebServiceWorkerContextClient.h",
       "web/modules/serviceworker/WebServiceWorkerContextProxy.h",
       "web/modules/serviceworker/WebServiceWorkerNetworkProvider.h",
       "web/modules/webmidi/WebMIDIClient.h",
       "web/modules/webmidi/WebMIDIOptions.h",
       "web/modules/webmidi/WebMIDIPermissionRequest.h",
       "web/win/WebFontRendering.h",
     ],
   },
 }