Add new latency_info for tracking browser composite time.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 2c57a2b78d543dafaff3170cf9d2447cc2ce5d62..7819365497b2b5ecc0f28ea6b69396a6a6212384 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -89,6 +89,9 @@ namespace {
 
 bool g_check_for_pending_resize_ack = true;
 
+const size_t kBrowserCompositeLatencyHistorySize = 60;
+const double kBrowserCompositeLatencyEstimationPercentile = 90.0;
+
 typedef std::pair<int32, int32> RenderWidgetHostID;
 typedef base::hash_map<RenderWidgetHostID, RenderWidgetHostImpl*>
     RoutingIDWidgetMap;
@@ -186,7 +189,8 @@ RenderWidgetHostImpl::RenderWidgetHostImpl(RenderWidgetHostDelegate* delegate,
       has_touch_handler_(false),
       weak_factory_(this),
       last_input_number_(static_cast<int64>(GetProcess()->GetID()) << 32),
-      next_browser_snapshot_id_(1) {
+      next_browser_snapshot_id_(1),
+      browser_composite_latency_history_(kBrowserCompositeLatencyHistorySize) {
   CHECK(delegate_);
   if (routing_id_ == MSG_ROUTING_NONE) {
     routing_id_ = process_->GetNextRoutingID();
@@ -1451,6 +1455,13 @@ bool RenderWidgetHostImpl::OnSwapCompositorFrame(
   input_router_->OnViewUpdated(
       GetInputRouterViewFlagsFromCompositorFrameMetadata(frame->metadata));
 
+  for (size_t i = 0; i < frame->metadata.latency_info.size(); ++i) {
+    frame->metadata.latency_info[i].AddLatencyNumber(
+        ui::INPUT_EVENT_RENDERER_SWAP_RECEIVED_COMPONENT,
+        GetLatencyComponentId(),
+        0);
+  }
+
   if (view_) {
     view_->OnSwapCompositorFrame(output_surface_id, frame.Pass());
     view_->DidReceiveRendererFrame();
@@ -2142,6 +2153,21 @@ void RenderWidgetHostImpl::FrameSwapped(const ui::LatencyInfo& latency_info) {
           100);
     }
   }
+
+  ui::LatencyInfo::LatencyComponent gpu_swap_component;
+  if (!latency_info.FindLatency(
+          ui::INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT, 0, &gpu_swap_component)) {
+    return;
+  }
+
+  ui::LatencyInfo::LatencyComponent composite_component;
+  if (latency_info.FindLatency(ui::INPUT_EVENT_RENDERER_SWAP_RECEIVED_COMPONENT,
+                               GetLatencyComponentId(),
+                               &composite_component)) {
+    base::TimeDelta delta =
+        gpu_swap_component.event_time - composite_component.event_time;
+    browser_composite_latency_history_.InsertSample(delta);
+  }
 }
 
 void RenderWidgetHostImpl::DidReceiveRendererFrame() {
@@ -2260,7 +2286,8 @@ void RenderWidgetHostImpl::CompositorFrameDrawn(
       if (b->first.first == ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT ||
           b->first.first == ui::WINDOW_SNAPSHOT_FRAME_NUMBER_COMPONENT ||
           b->first.first == ui::WINDOW_OLD_SNAPSHOT_FRAME_NUMBER_COMPONENT ||
-          b->first.first == ui::TAB_SHOW_COMPONENT) {
+          b->first.first == ui::TAB_SHOW_COMPONENT ||
+          b->first.first == ui::INPUT_EVENT_RENDERER_SWAP_RECEIVED_COMPONENT) {
         // Matches with GetLatencyComponentId
         int routing_id = b->first.second & 0xffffffff;
         int process_id = (b->first.second >> 32) & 0xffffffff;
@@ -2315,6 +2342,16 @@ BrowserAccessibilityManager*
       delegate_->GetOrCreateRootBrowserAccessibilityManager() : NULL;
 }
 
+base::TimeDelta RenderWidgetHostImpl::GetEstimatedBrowserCompositeTime() {
+  if (browser_composite_latency_history_.SampleCount() > 0) {
+    return browser_composite_latency_history_.Percentile(

[brianderson, 2014/09/22 22:59:35]

Let's add some slack to the estimate by multiplying the estimate by 110%.

[orglofch, 2014/09/22 23:55:14]

Done.

+        kBrowserCompositeLatencyEstimationPercentile);
+  } else {
+    return base::TimeDelta::FromMicroseconds(
+        (1.0f * base::Time::kMicrosecondsPerSecond) / (3.0f * 60));
+  }
+}
+
 #if defined(OS_WIN)
 gfx::NativeViewAccessible
     RenderWidgetHostImpl::GetParentNativeViewAccessible() {