cc metrics: Do not report throughput UMA for ui compositor.

Stop reporting the throughput metrics for the UI compositor, since it is
currently bundled with the throughput metrics for the renderer. We could
report these separately, but it's not clear that these would be used for
monitoring the UI performance.

BUG=1005226

Change-Id: Ia1572010737a66ecba114cfbb96239f822c1ea92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1810014
Reviewed-by: Behdad Bakhshinategh <behdadb@chromium.org>
Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697747}

cc/metrics/frame_sequence_tracker.cc

@@ -67,8 +67,10 @@ std::string GetFrameSequenceLengthHistogramName(FrameSequenceTrackerType type) {
 // FrameSequenceTrackerCollection
 
 FrameSequenceTrackerCollection::FrameSequenceTrackerCollection(
+    bool is_single_threaded,
     CompositorFrameReportingController* compositor_frame_reporting_controller)
-    : compositor_frame_reporting_controller_(
+    : is_single_threaded_(is_single_threaded),
+      compositor_frame_reporting_controller_(
           compositor_frame_reporting_controller) {
   StartSequence(FrameSequenceTrackerType::kUniversal);
 }
@@ -80,6 +82,8 @@ FrameSequenceTrackerCollection::~FrameSequenceTrackerCollection() {
 
 void FrameSequenceTrackerCollection::StartSequence(
     FrameSequenceTrackerType type) {
+  if (is_single_threaded_)
+    return;
   if (frame_trackers_.contains(type))
     return;
   auto tracker = base::WrapUnique(new FrameSequenceTracker(type));

cc/metrics/frame_sequence_tracker.h

@@ -48,8 +48,9 @@ enum FrameSequenceTrackerType {
 // submitted frames.
 class CC_EXPORT FrameSequenceTrackerCollection {
  public:
-  explicit FrameSequenceTrackerCollection(
-      CompositorFrameReportingController* = nullptr);
+  FrameSequenceTrackerCollection(
+      bool is_single_threaded,
+      CompositorFrameReportingController* frame_reporting_controller);
   ~FrameSequenceTrackerCollection();
 
   FrameSequenceTrackerCollection(const FrameSequenceTrackerCollection&) =
@@ -95,6 +96,7 @@ class CC_EXPORT FrameSequenceTrackerCollection {
  private:
   friend class FrameSequenceTrackerTest;
 
+  const bool is_single_threaded_;
   // The callsite can use the type to manipulate the tracker.
   base::flat_map<FrameSequenceTrackerType,
                  std::unique_ptr<FrameSequenceTracker>>

cc/metrics/frame_sequence_tracker_unittest.cc

@@ -22,7 +22,8 @@ class FrameSequenceTrackerTest : public testing::Test {
   FrameSequenceTrackerTest()
       : compositor_frame_reporting_controller_(
             std::make_unique<CompositorFrameReportingController>()),
-        collection_(compositor_frame_reporting_controller_.get()) {
+        collection_(/* is_single_threaded=*/false,
+                    compositor_frame_reporting_controller_.get()) {
     collection_.StartSequence(FrameSequenceTrackerType::kTouchScroll);
     tracker_ = collection_.GetTrackerForTesting(
         FrameSequenceTrackerType::kTouchScroll);

cc/trees/layer_tree_host_impl.cc

@@ -319,7 +319,8 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       is_animating_for_snap_(false),
       paint_image_generator_client_id_(PaintImage::GetNextGeneratorClientId()),
       scrollbar_controller_(std::make_unique<ScrollbarController>(this)),
-      frame_trackers_(compositor_frame_reporting_controller_.get()),
+      frame_trackers_(settings.single_thread_proxy_scheduler,
+                      compositor_frame_reporting_controller_.get()),
       scroll_gesture_did_end_(false) {
   DCHECK(mutator_host_);
   mutator_host_->SetMutatorHostClient(this);