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..27cb442c153b545662cdbc034cffd4c02b37372b 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 +1455,11 @@ 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_BROWSER_COMPOSITE_COMPONENT, 0, 0);

[brianderson, 2014/09/18 23:26:15]

If the Browser is swap or commit throttled, there may be a delay from when the
Renderer's swap is received to when it is actually consumed by the Browser.

For deadline estimation purposes, we care about the timing from when the swap is
consumed, not from when it is received.

Not sure where the best place to add an
INPUT_EVENT_RENDERER_SWAP_CONSUMED_COMPONENT is though...

The INPUT_EVENT_BROWSER_COMPOSITE_COMPONENT component would still be useful
though for test/debug purposes, so it might be nice to keep it here. Maybe call
it INPUT_EVENT_RENDERER_SWAP_RECEIVED_COMPONENT though?

[jbauman, 2014/09/19 20:40:29]

This should specify GetLatencyComponentId() as the component ID.

[orglofch, 2014/09/19 22:40:26]

@brian I've renamed the event.

[orglofch, 2014/09/19 22:40:26]

Done.

+  }
+
   if (view_) {
     view_->OnSwapCompositorFrame(output_surface_id, frame.Pass());
     view_->DidReceiveRendererFrame();
@@ -2142,6 +2151,21 @@ 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_BROWSER_COMPOSITE_COMPONENT,

[jbauman, 2014/09/19 20:40:29]

This should instead find the component with GetLatencyComponentId() as the
component id.

You'll also need to modify RenderWidgetHostImpl::CompositorFrameDrawn to route
the LatencyInfo to the correct RWHI based on that component id for this event.

[orglofch, 2014/09/19 22:40:26]

Done.

+                               0,
+                               &composite_component)) {
+    base::TimeDelta delta =
+        gpu_swap_component.event_time - composite_component.event_time;
+    browser_composite_latency_history_.InsertSample(delta);
+  }
 }
 
 void RenderWidgetHostImpl::DidReceiveRendererFrame() {
@@ -2315,6 +2339,16 @@ BrowserAccessibilityManager*
       delegate_->GetOrCreateRootBrowserAccessibilityManager() : NULL;
 }
 
+base::TimeDelta RenderWidgetHostImpl::GetEstimatedBrowserCompositeTime() {
+  if (browser_composite_latency_history_.SampleCount() > 0) {
+    return browser_composite_latency_history_.Percentile(
+        kBrowserCompositeLatencyEstimationPercentile);
+  } else {
+    return base::TimeDelta::FromMicroseconds(
+        (1.0f * base::Time::kMicrosecondsPerSecond) / (3.0f * 60));
+  }
+}
+
 #if defined(OS_WIN)
 gfx::NativeViewAccessible
     RenderWidgetHostImpl::GetParentNativeViewAccessible() {