FrameSinkIds use to WindowIds in window server, Process ID/Route ID in renderer

content/browser/renderer_host/render_widget_host_view_aura.cc

 // Copyright (c) 2012 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/renderer_host/render_widget_host_view_aura.h"
 
 #include <set>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 436 matching lines @@
       virtual_keyboard_requested_(false),
 #endif
       has_snapped_to_boundary_(false),
       is_guest_view_hack_(is_guest_view_hack),
       set_focus_on_mouse_down_or_key_event_(false),
       device_scale_factor_(0.0f),
       disable_input_event_router_for_testing_(false),
       last_active_widget_process_id_(ChildProcessHost::kInvalidUniqueID),
       last_active_widget_routing_id_(MSG_ROUTING_NONE),
       weak_ptr_factory_(this) {
+  // GuestViews have two RenderWidgetHostViews and so we need to make sure
+  // we don't have FrameSinkId collisions.
   ImageTransportFactory* factory = ImageTransportFactory::GetInstance();
-  delegated_frame_host_ = base::MakeUnique<DelegatedFrameHost>(
-      factory->GetContextFactory()->AllocateFrameSinkId(), this);
+  cc::FrameSinkId frame_sink_id =
+      is_guest_view_hack_
+          ? factory->GetContextFactory()->AllocateFrameSinkId()
+          : cc::FrameSinkId(
+                base::checked_cast<uint32_t>(host_->GetProcess()->GetID()),
+                base::checked_cast<uint32_t>(host_->GetRoutingID()));
+  delegated_frame_host_ =
+      base::MakeUnique<DelegatedFrameHost>(frame_sink_id, this);
 
   if (!is_guest_view_hack_)
     host_->SetView(this);
 
   // Let the page-level input event router know about our surface ID
   // namespace for surface-based hit testing.
   if (host_->delegate() && host_->delegate()->GetInputEventRouter()) {
     host_->delegate()->GetInputEventRouter()->AddFrameSinkIdOwner(
         GetFrameSinkId(), this);
   }
@@ skipping 2575 matching lines @@
           ->GetTextSelection(focused_view)
           ->GetSelectedText(&selected_text)) {
     // Set the CLIPBOARD_TYPE_SELECTION to the ui::Clipboard.
     ui::ScopedClipboardWriter clipboard_writer(ui::CLIPBOARD_TYPE_SELECTION);
     clipboard_writer.WriteText(selected_text);
   }
 #endif  // defined(USE_X11) && !defined(OS_CHROMEOS)
 }
 
 }  // namespace content