Revert of cc::SurfaceDependencyTracker should not crash when a Display goes away

cc/surfaces/primary_begin_frame_source.cc

Index: cc/surfaces/primary_begin_frame_source.cc
diff --git a/cc/surfaces/primary_begin_frame_source.cc b/cc/surfaces/primary_begin_frame_source.cc
deleted file mode 100644
index 588dbfae67e07ba6d65c40d3376d75e14e2d37ac..0000000000000000000000000000000000000000
--- a/cc/surfaces/primary_begin_frame_source.cc
+++ /dev/null
@@ -1,87 +0,0 @@
-// Copyright 2017 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 "cc/surfaces/primary_begin_frame_source.h"
-
-namespace cc {
-
-PrimaryBeginFrameSource::PrimaryBeginFrameSource()
-    : begin_frame_source_(this) {}
-
-PrimaryBeginFrameSource::~PrimaryBeginFrameSource() = default;
-
-void PrimaryBeginFrameSource::OnBeginFrameSourceAdded(
-    BeginFrameSource* begin_frame_source) {
-  sources_.insert(begin_frame_source);
-
-  if (current_begin_frame_source_)
-    return;
-
-  current_begin_frame_source_ = begin_frame_source;
-  if (needs_begin_frames_ && current_begin_frame_source_)
-    current_begin_frame_source_->AddObserver(this);
-}
-
-void PrimaryBeginFrameSource::OnBeginFrameSourceRemoved(
-    BeginFrameSource* begin_frame_source) {
-  sources_.erase(begin_frame_source);
-  if (current_begin_frame_source_ != begin_frame_source)
-    return;
-
-  if (needs_begin_frames_)
-    current_begin_frame_source_->RemoveObserver(this);
-
-  if (!sources_.empty())
-    current_begin_frame_source_ = *sources_.begin();
-  else
-    current_begin_frame_source_ = nullptr;
-
-  if (needs_begin_frames_ && current_begin_frame_source_)
-    current_begin_frame_source_->AddObserver(this);
-}
-
-void PrimaryBeginFrameSource::OnBeginFrame(const BeginFrameArgs& args) {
-  begin_frame_source_.OnBeginFrame(args);
-  last_begin_frame_args_ = args;
-}
-
-const BeginFrameArgs& PrimaryBeginFrameSource::LastUsedBeginFrameArgs() const {
-  return last_begin_frame_args_;
-}
-
-void PrimaryBeginFrameSource::OnBeginFrameSourcePausedChanged(bool paused) {}
-
-void PrimaryBeginFrameSource::DidFinishFrame(BeginFrameObserver* obs,
-                                             const BeginFrameAck& ack) {
-  begin_frame_source_.DidFinishFrame(obs, ack);
-}
-
-void PrimaryBeginFrameSource::AddObserver(BeginFrameObserver* obs) {
-  begin_frame_source_.AddObserver(obs);
-}
-
-void PrimaryBeginFrameSource::RemoveObserver(BeginFrameObserver* obs) {
-  begin_frame_source_.RemoveObserver(obs);
-}
-
-bool PrimaryBeginFrameSource::IsThrottled() const {
-  return begin_frame_source_.IsThrottled();
-}
-
-void PrimaryBeginFrameSource::OnNeedsBeginFrames(bool needs_begin_frames) {
-  if (needs_begin_frames_ == needs_begin_frames)
-    return;
-
-  needs_begin_frames_ = needs_begin_frames;
-
-  if (!current_begin_frame_source_)
-    return;
-
-  if (needs_begin_frames_)
-    current_begin_frame_source_->AddObserver(this);
-  else
-    current_begin_frame_source_->RemoveObserver(this);
-}
-
-}  // namespace cc