From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Andy Locascio <andy@slack-corp.com>
Date: Wed, 21 Aug 2019 12:09:10 -0700
Subject: fix: disabling compositor recycling

Compositor recycling is useful for Chrome because there can be many tabs and spinning up a compositor for each one would be costly. In practice, Chrome uses the parent compositor code path of browser_compositor_view_mac.mm; the NSView of each tab is detached when it's hidden and attached when it's shown. For Electron, there is no parent compositor, so we're forced into the "own compositor" code path, which seems to be non-optimal and pretty ruthless in terms of the release of resources. Electron has no real concept of multiple tabs per window, so it should be okay to disable this ruthless recycling altogether in Electron.

diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 58002d37ba340f84f47e2522c0d7bf7c1a64c5d2..bc0a73f08e77bf13eb1cafa55f955e6083071104 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -510,7 +510,11 @@
     return;
 
   host()->WasHidden();
-  browser_compositor_->SetRenderWidgetHostIsHidden(true);
+  // Consider the RWHV occluded only if it is not attached to a window
+  // (e.g. unattached BrowserView). Otherwise we treat it as visible to
+  // prevent unnecessary compositor recycling.
+  const bool unattached = ![GetInProcessNSView() window];
+  browser_compositor_->SetRenderWidgetHostIsHidden(unattached);
 }
 
 void RenderWidgetHostViewMac::SetSize(const gfx::Size& size) {