Update presentation time calculations.

As per the spec, the driver is expected to return a valid timestamp from
the call eglGetFrameTimestampsANDROID() when its not
EGL_TIMESTAMP_PENDING_ANDROID or EGL_TIMESTAMP_INVALID_ANDROID.
But currently few buggy drivers returns an invalid timestamp 0.

We fix/workaround this in chrome by returning the presentation time
as TimeTicks::Now() (snapped to the next vsync) instead of 0.

Bug: 966638
Change-Id: I5075dda0739f02029922ebbc20c09656fb0e87ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1631354Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: vikas soni <vikassoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663918}

ui/gl/gl_surface_egl.cc

@@ -1477,6 +1477,15 @@ bool NativeViewGLSurfaceEGL::GetFrameTimestampInfoIfAvailable(
   // reporting purpose.
   std::vector<EGLnsecsANDROID> egl_timestamps(supported_egl_timestamps_.size(),
                                               EGL_TIMESTAMP_INVALID_ANDROID);
+
+  // TODO(vikassoni): File a driver bug for eglGetFrameTimestampsANDROID().
+  // See https://bugs.chromium.org/p/chromium/issues/detail?id=966638.
+  // As per the spec, the driver is expected to return a valid timestamp from
+  // the call eglGetFrameTimestampsANDROID() when its not
+  // EGL_TIMESTAMP_PENDING_ANDROID or EGL_TIMESTAMP_INVALID_ANDROID. But
+  // currently some buggy drivers an invalid timestamp 0.
+  // This is currentlt handled in chrome for by setting the presentation time to
+  // TimeTicks::Now() (snapped to the next vsync) instead of 0.
   if ((frame_id < 0) ||
       !eglGetFrameTimestampsANDROID(
           GetDisplay(), surface_, frame_id,
@@ -1512,7 +1521,6 @@ bool NativeViewGLSurfaceEGL::GetFrameTimestampInfoIfAvailable(
                          base::TimeDelta::FromNanoseconds(presentation_time_ns);
     *presentation_flags = presentation_flags_;
   }
-  DCHECK(!presentation_time->is_null());
   return true;
 }
 

ui/gl/gl_surface_presentation_helper.cc

@@ -70,8 +70,24 @@ bool GLSurfacePresentationHelper::GetFrameTimestampInfoIfAvailable(
   DCHECK(frame.timer || frame.fence || egl_timestamp_client_);
 
   if (egl_timestamp_client_) {
-    return egl_timestamp_client_->GetFrameTimestampInfoIfAvailable(
+    bool result = egl_timestamp_client_->GetFrameTimestampInfoIfAvailable(
         timestamp, interval, flags, frame.frame_id);
+
+    // Workaround null timestamp by setting it to TimeTicks::Now() snapped to
+    // the next vsync interval. See
+    // https://bugs.chromium.org/p/chromium/issues/detail?id=966638 for more
+    // details.
+    if (result && timestamp->is_null()) {
+      *timestamp = base::TimeTicks::Now();
+      *interval = vsync_interval_;
+      *flags = 0;
+      if (!vsync_interval_.is_zero()) {
+        *timestamp =
+            timestamp->SnappedToNextTick(vsync_timebase_, vsync_interval_);
+        *flags = gfx::PresentationFeedback::kVSync;
+      }
+    }
+    return result;
   } else if (frame.timer) {
     if (!frame.timer->IsAvailable())
       return false;