[AW] Added latency tracking.

Using a ui::LatencyTracker to record all collected latency info
after drawing buffers have been swapped. This records a system health
metric (Event.Latency.ScrollBegin.Wheel.TimeToScrollUpdateSwapBegin4)
as well as the recording of latency info for debugging.

Bug: 992026
Change-Id: I904cbec84418426f06c9b237c2ead86566570302
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1929264Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Chris Mumford <cmumford@google.com>
Cr-Commit-Position: refs/heads/master@{#718330}

android_webview/browser/gfx/DEPS

@@ -7,5 +7,6 @@ include_rules = [
   "+android_webview/common/aw_switches.h",
   "+android_webview/public/browser",
   "+components/viz/service/main",
+  "+ui/latency",
 ]
 

android_webview/browser/gfx/parent_output_surface.cc

@@ -14,6 +14,21 @@
 
 namespace android_webview {
 
+namespace {
+
+void AddLatencyInfoSwapTimes(std::vector<ui::LatencyInfo>* latency_info,
+                             base::TimeTicks swap_start,
+                             base::TimeTicks swap_end) {
+  for (auto& latency : *latency_info) {
+    latency.AddLatencyNumberWithTimestamp(
+        ui::INPUT_EVENT_GPU_SWAP_BUFFER_COMPONENT, swap_start);
+    latency.AddLatencyNumberWithTimestamp(
+        ui::INPUT_EVENT_LATENCY_FRAME_SWAP_COMPONENT, swap_end);
+  }
+}
+
+}  // namespace
+
 ParentOutputSurface::ParentOutputSurface(
     scoped_refptr<AwGLSurface> gl_surface,
     scoped_refptr<AwRenderThreadContextProvider> context_provider)
@@ -49,13 +64,20 @@ void ParentOutputSurface::Reshape(const gfx::Size& size,
 
 void ParentOutputSurface::SwapBuffers(viz::OutputSurfaceFrame frame) {
   context_provider_->ContextGL()->ShallowFlushCHROMIUM();
-  gl_surface_->SwapBuffers(base::BindOnce(&ParentOutputSurface::OnPresentation,
-                                          weak_ptr_factory_.GetWeakPtr()));
+  gl_surface_->SwapBuffers(base::BindOnce(
+      &ParentOutputSurface::OnPresentation, weak_ptr_factory_.GetWeakPtr(),
+      /*swap_start=*/base::TimeTicks::Now(), std::move(frame.latency_info)));
 }
 
 void ParentOutputSurface::OnPresentation(
+    base::TimeTicks swap_start,
+    std::vector<ui::LatencyInfo> latency_info,
     const gfx::PresentationFeedback& feedback) {
   DCHECK(client_);
+  // The start/end swap times are only best-effort. It is not possible to get
+  // the real swap times for WebView.
+  AddLatencyInfoSwapTimes(&latency_info, swap_start, base::TimeTicks::Now());
+  latency_tracker_.OnGpuSwapBuffersCompleted(latency_info);
   client_->DidReceivePresentationFeedback(feedback);
 }
 

android_webview/browser/gfx/parent_output_surface.h

@@ -5,11 +5,15 @@
 #ifndef ANDROID_WEBVIEW_BROWSER_GFX_PARENT_OUTPUT_SURFACE_H_
 #define ANDROID_WEBVIEW_BROWSER_GFX_PARENT_OUTPUT_SURFACE_H_
 
+#include <vector>
+
 #include "android_webview/browser/gfx/aw_gl_surface.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "components/viz/service/display/output_surface.h"
+#include "ui/latency/latency_info.h"
+#include "ui/latency/latency_tracker.h"
 
 namespace gfx {
 struct PresentationFeedback;
@@ -50,12 +54,15 @@ class ParentOutputSurface : public viz::OutputSurface {
   gfx::OverlayTransform GetDisplayTransform() override;
 
  private:
-  void OnPresentation(const gfx::PresentationFeedback& feedback);
+  void OnPresentation(base::TimeTicks swap_start,
+                      std::vector<ui::LatencyInfo> latency_info,
+                      const gfx::PresentationFeedback& feedback);
 
   viz::OutputSurfaceClient* client_ = nullptr;
   // This is really a layering violation but needed for hooking up presentation
   // feedbacks properly.
   scoped_refptr<AwGLSurface> gl_surface_;
+  ui::LatencyTracker latency_tracker_;
   base::WeakPtrFactory<ParentOutputSurface> weak_ptr_factory_{this};
   DISALLOW_COPY_AND_ASSIGN(ParentOutputSurface);
 };