cc: Abstract the LayerTreeHost.

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index 1b28c6d7d8ec91baf0d9cf2a6949e0e05b36e0db..e608a32d53e3b9256b1b6b40978d00dde9644764 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -63,10 +63,9 @@ void SingleThreadProxy::Start(
   DebugScopedSetImplThread impl(task_runner_provider_);
   external_begin_frame_source_ = std::move(external_begin_frame_source);
 
-  if (layer_tree_host_->settings().single_thread_proxy_scheduler &&
-      !scheduler_on_impl_thread_) {
-    SchedulerSettings scheduler_settings(
-        layer_tree_host_->settings().ToSchedulerSettings());
+  const LayerTreeSettings& settings = layer_tree_host_->GetSettings();
+  if (settings.single_thread_proxy_scheduler && !scheduler_on_impl_thread_) {
+    SchedulerSettings scheduler_settings(settings.ToSchedulerSettings());
     scheduler_settings.commit_to_active_tree = CommitToActiveTree();
 
     std::unique_ptr<CompositorTimingHistory> compositor_timing_history(
@@ -79,15 +78,14 @@ void SingleThreadProxy::Start(
     // external, it must be provided.  If from the output surface, it must
     // not be provided.
     // TODO(enne): Make all BFS come from the output surface.
-    DCHECK(layer_tree_host_->settings().use_external_begin_frame_source ^
-           layer_tree_host_->settings().use_output_surface_begin_frame_source);
-    DCHECK(!layer_tree_host_->settings().use_external_begin_frame_source ||
+    DCHECK(settings.use_external_begin_frame_source ^
+           settings.use_output_surface_begin_frame_source);
+    DCHECK(!settings.use_external_begin_frame_source ||
            external_begin_frame_source_);
-    DCHECK(
-        !layer_tree_host_->settings().use_output_surface_begin_frame_source ||
-        !external_begin_frame_source_);
+    DCHECK(!settings.use_output_surface_begin_frame_source ||
+           !external_begin_frame_source_);
     scheduler_on_impl_thread_ =
-        Scheduler::Create(this, scheduler_settings, layer_tree_host_->id(),
+        Scheduler::Create(this, scheduler_settings, layer_tree_host_->GetId(),
                           task_runner_provider_->MainThreadTaskRunner(),
                           external_begin_frame_source_.get(),
                           std::move(compositor_timing_history));
@@ -194,7 +192,7 @@ void SingleThreadProxy::DoCommit() {
       FROM_HERE_WITH_EXPLICIT_FUNCTION("461509 SingleThreadProxy::DoCommit1"));
   layer_tree_host_->WillCommit();
   devtools_instrumentation::ScopedCommitTrace commit_task(
-      layer_tree_host_->id());
+      layer_tree_host_->GetId());
 
   // Commit immediately.
   {
@@ -457,10 +455,10 @@ void SingleThreadProxy::DidLoseOutputSurfaceOnImplThread() {
 }
 
 void SingleThreadProxy::SetBeginFrameSource(BeginFrameSource* source) {
-  DCHECK(layer_tree_host_->settings().single_thread_proxy_scheduler);
+  DCHECK(layer_tree_host_->GetSettings().single_thread_proxy_scheduler);
   // TODO(enne): this overrides any preexisting begin frame source.  Those
   // other sources will eventually be removed and this will be the only path.
-  if (!layer_tree_host_->settings().use_output_surface_begin_frame_source)
+  if (!layer_tree_host_->GetSettings().use_output_surface_begin_frame_source)
     return;
   if (scheduler_on_impl_thread_)
     scheduler_on_impl_thread_->SetBeginFrameSource(source);
@@ -731,7 +729,7 @@ void SingleThreadProxy::BeginMainFrame(const BeginFrameArgs& begin_frame_args) {
   // commit.
   ScopedAbortRemainingSwapPromises swap_promise_checker(layer_tree_host_);
 
-  if (!layer_tree_host_->visible()) {
+  if (!layer_tree_host_->IsVisible()) {
     TRACE_EVENT_INSTANT0("cc", "EarlyOut_NotVisible", TRACE_EVENT_SCOPE_THREAD);
     BeginMainFrameAbortedOnImplThread(
         CommitEarlyOutReason::ABORTED_NOT_VISIBLE);