cc: Plumbing for BeginFrameSource based on Surfaces

cc/surfaces/surface.cc

Index: cc/surfaces/surface.cc
diff --git a/cc/surfaces/surface.cc b/cc/surfaces/surface.cc
index 16987cb84e49b356bd2cf4afa0fd255f9ddf82a6..5fcba9f2b18eaa3c1bf683de1e170b9cde1f6919 100644
--- a/cc/surfaces/surface.cc
+++ b/cc/surfaces/surface.cc
@@ -14,6 +14,14 @@
 
 namespace cc {
 
+namespace {
+template <typename Collection, typename Value>
+void EraseValueAndCompact(Collection* collection, const Value& value) {
+  collection->erase(std::remove(collection->begin(), collection->end(), value),
+                    collection->end());
+}
+}  // namespace
+
 // The frame index starts at 2 so that empty frames will be treated as
 // completely damaged the first time they're drawn from.
 static const int kFrameIndexStart = 2;
@@ -35,6 +43,9 @@ Surface::~Surface() {
   }
   if (!draw_callback_.is_null())
     draw_callback_.Run(SurfaceDrawStatus::DRAW_SKIPPED);
+
+  if (factory_)
+    factory_->SetBeginFrameSource(surface_id_, NULL);
 }
 
 void Surface::QueueFrame(scoped_ptr<CompositorFrame> frame,
@@ -164,6 +175,44 @@ void Surface::SatisfyDestructionDependencies(
       destruction_dependencies_.end());
 }
 
+void Surface::AddBeginFrameSource(BeginFrameSource* begin_frame_source) {
+  DCHECK(base::STLIsSorted(begin_frame_sources_));
+
+  // Find the insertion point.
+  auto insert_index = begin_frame_sources_.begin();
+  while (insert_index != begin_frame_sources_.end()) {
+    if (begin_frame_source < *insert_index)
+      break;
+    insert_index++;
+  }
+
+  // Verify it doesn't already exist and insert it.
+  DCHECK(insert_index == begin_frame_sources_.end() ||
+         *insert_index != begin_frame_source);
+  begin_frame_sources_.insert(insert_index, begin_frame_source);
+  UpdatePrimaryBeginFrameSource();
+}
+
+void Surface::RemoveBeginFrameSource(BeginFrameSource* begin_frame_source) {
+  DCHECK(ContainsValue(begin_frame_sources_, begin_frame_source));
+  EraseValueAndCompact(&begin_frame_sources_, begin_frame_source);
+  UpdatePrimaryBeginFrameSource();
+}
+
+void Surface::UpdatePrimaryBeginFrameSource() {
+  // Ensure the BeginFrameSources are sorted so our we make a stable decision
+  // regarding which source is primary.
+  // TODO(brianderson): Do something smarter based on coverage instead.
+  DCHECK(base::STLIsSorted(begin_frame_sources_));
+
+  BeginFrameSource* primary_source = nullptr;
+  if (!begin_frame_sources_.empty())
+    primary_source = begin_frame_sources_[0];
+
+  if (factory_)
+    factory_->SetBeginFrameSource(surface_id_, primary_source);
+}
+
 void Surface::ClearCopyRequests() {
   if (current_frame_) {
     for (const auto& render_pass :