Add BlimpDocument, pull out functions in BlimpCompositor.

blimp/client/core/feedback/blimp_feedback_data.cc

 // Copyright 2016 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 "blimp/client/core/feedback/blimp_feedback_data.h"
 
 #include "blimp/client/core/contents/blimp_contents_manager.h"
 
 namespace blimp {
 namespace client {
 const char kFeedbackSupportedKey[] = "Blimp Supported";
 const char kFeedbackHasVisibleBlimpContents[] = "Blimp Visible";
 
 namespace {
 std::string HasVisibleBlimpContents(
     BlimpContentsManager* blimp_contents_manager) {
   std::vector<BlimpContentsImpl*> all_blimp_contents =
       blimp_contents_manager->GetAllActiveBlimpContents();
   for (const auto& item : all_blimp_contents) {
-    if (item->compositor_manager()->visible()) {
+    if (item->document_manager()->visible()) {
       return "true";
     }
   }
   return "false";
 }
 }  // namespace
 
 std::unordered_map<std::string, std::string> CreateBlimpFeedbackData(
     BlimpContentsManager* blimp_contents_manager) {
   std::unordered_map<std::string, std::string> data;
   data.insert(std::make_pair(kFeedbackSupportedKey, "true"));
   data.insert(std::make_pair(kFeedbackHasVisibleBlimpContents,
                              HasVisibleBlimpContents(blimp_contents_manager)));
   return data;
 }
 
 }  // namespace client
 }  // namespace blimp