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

cc/surfaces/frame_sink_manager.cc

 // 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.
 
 #include "cc/surfaces/frame_sink_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/logging.h"
 #include "cc/surfaces/frame_sink_manager_client.h"
+#include "cc/surfaces/primary_begin_frame_source.h"
 
 #if DCHECK_IS_ON()
 #include <sstream>
 #endif
 
 namespace cc {
 
-FrameSinkManager::FrameSinkSourceMapping::FrameSinkSourceMapping()
-    : source(nullptr) {}
+FrameSinkManager::FrameSinkSourceMapping::FrameSinkSourceMapping() = default;
 
 FrameSinkManager::FrameSinkSourceMapping::FrameSinkSourceMapping(
     const FrameSinkSourceMapping& other) = default;
 
-FrameSinkManager::FrameSinkSourceMapping::~FrameSinkSourceMapping() {}
+FrameSinkManager::FrameSinkSourceMapping::~FrameSinkSourceMapping() = default;
 
-FrameSinkManager::FrameSinkManager() {}
+FrameSinkManager::FrameSinkManager() = default;
 
 FrameSinkManager::~FrameSinkManager() {
   // All CompositorFrameSinks should be unregistered prior to
   // SurfaceManager destruction.
   DCHECK_EQ(clients_.size(), 0u);
   DCHECK_EQ(registered_sources_.size(), 0u);
 }
 
 void FrameSinkManager::RegisterFrameSinkId(const FrameSinkId& frame_sink_id) {
   bool inserted = valid_frame_sink_ids_.insert(frame_sink_id).second;
@@ skipping 28 matching lines @@
   auto source_iter = frame_sink_source_map_.find(frame_sink_id);
   if (source_iter != frame_sink_source_map_.end()) {
     if (source_iter->second.source)
       client_iter->second->SetBeginFrameSource(nullptr);
     if (!source_iter->second.has_children())
       frame_sink_source_map_.erase(source_iter);
   }
   clients_.erase(client_iter);
 }
 
+std::unique_ptr<BeginFrameSource>
+FrameSinkManager::CreatePrimaryBeginFrameSource() {
+  std::unique_ptr<PrimaryBeginFrameSource> begin_frame_source =
+      base::MakeUnique<PrimaryBeginFrameSource>();
+  begin_frame_source->Init(this);
+  return std::move(begin_frame_source);
+}
+
 void FrameSinkManager::RegisterBeginFrameSource(
     BeginFrameSource* source,
     const FrameSinkId& frame_sink_id) {
   DCHECK(source);
   DCHECK_EQ(registered_sources_.count(source), 0u);
   DCHECK_EQ(valid_frame_sink_ids_.count(frame_sink_id), 1u);
 
   registered_sources_[source] = frame_sink_id;
   RecursivelyAttachBeginFrameSource(frame_sink_id, source);
+
+  for (auto& observer : observer_list_)
+    observer.OnBeginFrameSourceAdded(source);
 }
 
 void FrameSinkManager::UnregisterBeginFrameSource(BeginFrameSource* source) {
   DCHECK(source);
   DCHECK_EQ(registered_sources_.count(source), 1u);
 
   FrameSinkId frame_sink_id = registered_sources_[source];
   registered_sources_.erase(source);
 
+  for (auto& observer : observer_list_)
+    observer.OnBeginFrameSourceRemoved(source);
+
   if (frame_sink_source_map_.count(frame_sink_id) == 0u)
     return;
 
   // TODO(enne): these walks could be done in one step.
   // Remove this begin frame source from its subtree.
   RecursivelyDetachBeginFrameSource(frame_sink_id, source);
   // Then flush every remaining registered source to fix any sources that
   // became null because of the previous step but that have an alternative.
   for (auto source_iter : registered_sources_)
     RecursivelyAttachBeginFrameSource(source_iter.second, source_iter.first);
 }
 
+BeginFrameSource* FrameSinkManager::GetPrimaryBeginFrameSource() {
+  if (registered_sources_.empty())
+    return nullptr;
+  return registered_sources_.begin()->first;
+}
+
 void FrameSinkManager::RecursivelyAttachBeginFrameSource(
     const FrameSinkId& frame_sink_id,
     BeginFrameSource* source) {
   FrameSinkSourceMapping& mapping = frame_sink_source_map_[frame_sink_id];
   if (!mapping.source) {
     mapping.source = source;
     auto client_iter = clients_.find(frame_sink_id);
     if (client_iter != clients_.end())
       client_iter->second->SetBeginFrameSource(source);
   }
@@ skipping 105 matching lines @@
   if (!parent_source)
     return;
 
   // TODO(enne): these walks could be done in one step.
   RecursivelyDetachBeginFrameSource(child_frame_sink_id, parent_source);
   for (auto source_iter : registered_sources_)
     RecursivelyAttachBeginFrameSource(source_iter.second, source_iter.first);
 }
 
 }  // namespace cc