electron/patches/chromium/fix_disabling_background_throttling_in_compositor.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Michal Pichlinski <[email protected]>
Date: Thu, 15 Jun 2023 23:04:48 +0200
Subject: allow disabling throttling in the `viz::DisplayScheduler` per
 `ui::Compositor`

In Chromium when the `viz::DisplayScheduler` is invisible it throttles
its work by dropping frame draws and swaps.

This patch allows disbling this throttling by preventing transition to
invisible state of the `viz::DisplayScheduler` owned
by the `ui::Compositor`.

diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 64775be482d47143fb56d815d390bd56875e8493..347f135c75c226faec33199909cc5ee4a8924a24 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -338,7 +338,8 @@ void Compositor::SetLayerTreeFrameSink(
   if (display_private_) {
     disabled_swap_until_resize_ = false;
     display_private_->Resize(size());
-    display_private_->SetDisplayVisible(host_->IsVisible());
+    // Invisible display is throttling itself.
+    display_private_->SetDisplayVisible(background_throttling_ ? host_->IsVisible() : true);
     display_private_->SetDisplayColorSpaces(display_color_spaces_);
     display_private_->SetDisplayColorMatrix(
         gfx::SkM44ToTransform(display_color_matrix_));
@@ -530,8 +531,11 @@ void Compositor::SetVisible(bool visible) {
   host_->SetVisible(visible);
   // Visibility is reset when the output surface is lost, so this must also be
   // updated then.
-  if (display_private_)
-    display_private_->SetDisplayVisible(visible);
+  if (display_private_) {
+    // Invisible display is throttling itself.
+    display_private_->SetDisplayVisible(
+        background_throttling_ ? visible : true);
+  }
 }
 
 bool Compositor::IsVisible() {
@@ -958,4 +962,13 @@ const cc::LayerTreeSettings& Compositor::GetLayerTreeSettings() const {
   return host_->GetSettings();
 }
 
+void Compositor::SetBackgroundThrottling(bool background_throttling_enabled) {
+  background_throttling_ = background_throttling_enabled;
+  if (display_private_) {
+    // Invisible display is throttling itself.
+    display_private_->SetDisplayVisible(
+        background_throttling_ ? host_->IsVisible() : true);
+  }
+}
+
 }  // namespace ui
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index e1781e682f2e1217fe4cc7ab26cd82e7bcc352e7..2cd96e3518b9a62091a69782b65ef61a8e798022 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -522,6 +522,10 @@ class COMPOSITOR_EXPORT Compositor : public base::PowerSuspendObserver,
     return host_->saved_events_metrics_count_for_testing();
   }
 
+  // Sets |background_throttling_| responsible for suspending drawing
+  // and switching frames.
+  void SetBackgroundThrottling(bool background_throttling_enabled);
+
  private:
   friend class base::RefCounted<Compositor>;
   friend class TotalAnimationThroughputReporter;
@@ -628,6 +632,12 @@ class COMPOSITOR_EXPORT Compositor : public base::PowerSuspendObserver,
   // See go/report-ux-metrics-at-painting for details.
   bool animation_started_ = false;
 
+  // Background throttling is a default Chromium behaviour. It occurs
+  // when the |display_private_| is not visible by prevent drawing and swapping
+  // frames. When it is disabled we are keeping |display_private_| always
+  // visible in order to keep generating frames.
+  bool background_throttling_ = true;
+
   TrackerId next_throughput_tracker_id_ = 1u;
   struct TrackerState {
     TrackerState();