WIP: Bug 1708121, keep ticking after page load r=mstange

Differential Revision: https://phabricator.services.mozilla.com/D116040

dom/base/nsDOMNavigationTiming.h

@@ -202,6 +202,8 @@ class nsDOMNavigationTiming final : public mozilla::RelativeTimeline {
     return mDocShellHasBeenActiveSinceNavigationStart;
   }
 
+  mozilla::TimeStamp LoadEventEnd() { return mLoadEventEnd; }
+
  private:
   friend class nsDocShell;
   nsDOMNavigationTiming(nsDocShell* aDocShell, nsDOMNavigationTiming* aOther);

layout/base/nsRefreshDriver.cpp

@@ -51,6 +51,7 @@
 #include "nsContentUtils.h"
 #include "mozilla/PendingAnimationTracker.h"
 #include "mozilla/PendingFullscreenEvent.h"
+#include "mozilla/dom/PerformanceMainThread.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/StaticPrefs_apz.h"
 #include "mozilla/StaticPrefs_gfx.h"
@@ -84,6 +85,7 @@
 #include "mozilla/TimelineConsumers.h"
 #include "nsAnimationManager.h"
 #include "nsDisplayList.h"
+#include "nsDOMNavigationTiming.h"
 #include "nsTransitionManager.h"
 
 #if defined(MOZ_WIDGET_ANDROID)
@@ -1131,6 +1133,7 @@ nsRefreshDriver::nsRefreshDriver(nsPresContext* aPresContext)
       mNeedToUpdateIntersectionObservations(false),
       mInNormalTick(false),
       mAttemptedExtraTickSinceLastVsync(false),
+      mHasExceededAfterLoadTickPeriod(false),
       mWarningThreshold(REFRESH_WAIT_WARNING) {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(mPresContext,
@@ -1735,6 +1738,43 @@ bool nsRefreshDriver::
   return TimeStamp::Now() <= mBeforeFirstContentfulPaintTimerRunningLimit;
 }
 
+bool nsRefreshDriver::ShouldKeepTimerRunningAfterPageLoad() {
+  if (mHasExceededAfterLoadTickPeriod ||
+      !StaticPrefs::layout_keep_ticking_after_load_ms() || mThrottled ||
+      mTestControllingRefreshes || !XRE_IsContentProcess() ||
+      !mPresContext->Document()->IsTopLevelContentDocument() ||
+      gfxPlatform::IsInLayoutAsapMode()) {
+    // Make the next check faster.
+    mHasExceededAfterLoadTickPeriod = true;
+    return false;
+  }
+
+  nsPIDOMWindowInner* innerWindow = mPresContext->Document()->GetInnerWindow();
+  if (innerWindow) {
+    if (PerformanceMainThread* perf = static_cast<PerformanceMainThread*>(
+            innerWindow->GetPerformance())) {
+      nsDOMNavigationTiming* timing = perf->GetDOMTiming();
+      if (timing) {
+        TimeStamp loadend = timing->LoadEventEnd();
+        if (loadend) {
+          // Keep ticking after the page load for some time.
+          bool retval =
+              (loadend +
+               TimeDuration::FromMilliseconds(
+                   StaticPrefs::layout_keep_ticking_after_load_ms())) >
+              TimeStamp::Now();
+          if (!retval) {
+            mHasExceededAfterLoadTickPeriod = true;
+          }
+          return retval;
+        }
+      }
+    }
+  }
+
+  return false;
+}
+
 nsRefreshDriver::ObserverArray& nsRefreshDriver::ArrayFor(
     FlushType aFlushType) {
   switch (aFlushType) {
@@ -2107,6 +2147,11 @@ void nsRefreshDriver::Tick(VsyncId aId, TimeStamp aNowTime,
           "RefreshDriverTick waiting for first contentful paint", GRAPHICS,
           MarkerInnerWindowIdFromDocShell(GetDocShell(mPresContext)), Tracing,
           "Paint");
+    } else if (ShouldKeepTimerRunningAfterPageLoad()) {
+      PROFILER_MARKER(
+          "RefreshDriverTick after page load", GRAPHICS,
+          MarkerInnerWindowIdFromDocShell(GetDocShell(mPresContext)), Tracing,
+          "Paint");
     } else {
       StopTimer();
     }

layout/base/nsRefreshDriver.h

@@ -480,6 +480,7 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   uint32_t ObserverCount() const;
   bool HasImageRequests() const;
   bool ShouldKeepTimerRunningWhileWaitingForFirstContentfulPaint();
+  bool ShouldKeepTimerRunningAfterPageLoad();
   ObserverArray& ArrayFor(mozilla::FlushType aFlushType);
   // Trigger a refresh immediately, if haven't been disconnected or frozen.
   void DoRefresh();
@@ -590,6 +591,8 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   // vsync and thus shouldn't allow another.
   bool mAttemptedExtraTickSinceLastVsync : 1;
 
+  bool mHasExceededAfterLoadTickPeriod : 1;
+
   // Number of seconds that the refresh driver is blocked waiting for a
   // compositor transaction to be completed before we append a note to the gfx
   // critical log. The number is doubled every time the threshold is hit.

modules/libpref/init/StaticPrefList.yaml

@@ -7331,6 +7331,13 @@
   value: true
   mirror: always
 
+# If > 0, nsRefreshDriver will keep ticking this amount of milliseconds after
+# top level page load.
+- name: layout.keep_ticking_after_load_ms
+  type: uint32_t
+  value: 1000
+  mirror: always
+
 # Is layout of CSS outline-style:auto enabled?
 - name: layout.css.outline-style-auto.enabled
   type: bool