Bug 1726712 - Only do a shrinking GC if we're not animating r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D124014

dom/base/CCGCScheduler.cpp

@@ -7,6 +7,7 @@
 #include "mozilla/StaticPrefs_javascript.h"
 #include "mozilla/CycleCollectedJSRuntime.h"
 #include "mozilla/dom/ScriptSettings.h"
+#include "nsRefreshDriver.h"
 
 namespace mozilla {
 
@@ -115,11 +116,20 @@ bool CCGCScheduler::GCRunnerFiredDoGC(TimeStamp aDeadline,
   // Run a GC slice, possibly the first one of a major GC.
   nsJSContext::IsShrinking is_shrinking = nsJSContext::NonShrinkingGC;
   if (!InIncrementalGC() && aStep.mReason == JS::GCReason::USER_INACTIVE) {
+    bool do_gc = mWantAtLeastRegularGC;
+
     if (!mUserIsActive) {
-      mIsCompactingOnUserInactive = true;
-      is_shrinking = nsJSContext::ShrinkingGC;
-    } else if (!mWantAtLeastRegularGC) {
-      // Don't GC now.
+      if (!nsRefreshDriver::IsRegularRateTimerTicking()) {
+        mIsCompactingOnUserInactive = true;
+        is_shrinking = nsJSContext::ShrinkingGC;
+        do_gc = true;
+      } else {
+        // Poke again to restart the timer.
+        PokeShrinkingGC();
+      }
+    }
+
+    if (!do_gc) {
       using mozilla::ipc::IdleSchedulerChild;
       IdleSchedulerChild* child =
           IdleSchedulerChild::GetMainThreadIdleScheduler();
@@ -233,8 +243,14 @@ void CCGCScheduler::PokeShrinkingGC() {
       [](nsITimer* aTimer, void* aClosure) {
         CCGCScheduler* s = static_cast<CCGCScheduler*>(aClosure);
         s->KillShrinkingGCTimer();
-        s->SetWantMajorGC(JS::GCReason::USER_INACTIVE);
-        s->EnsureGCRunner(0);
+        if (!s->mUserIsActive) {
+          if (!nsRefreshDriver::IsRegularRateTimerTicking()) {
+            s->SetWantMajorGC(JS::GCReason::USER_INACTIVE);
+            s->EnsureGCRunner(0);
+          } else {
+            s->PokeShrinkingGC();
+          }
+        }
       },
       this, StaticPrefs::javascript_options_compact_on_user_inactive_delay(),
       nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY, "ShrinkingGCTimerFired");