Bug 1668878 - Stop doing catch-up composites on webrender. r=mattwoodrow

Currently, when webrender fails to render a frame on time, it will
attempt to catch up by rendering the next frame immediately (part way
through the vsync period) rather than delaying until the next
vsync. The idea is that even though the first frame missed vsync, the
next frame can hopefully still be rendered on time.

However, on Android, because of the default EGL swap interval of zero,
the driver blocks rather than allowing 2 frames to be rendered in a
single vsync. This guarantees that the next frame will also miss its
vsync, and so on. Other platforms may avoid this by setting the swap
interval to zero. While that was an option on Android too, it was felt
that the premise of catch up composites was still flawed: a
late-started composite is unlikely to meet its deadline, even if the
driver does not block. Better to cut our losses and wait for the next
vsync.

Differential Revision: https://phabricator.services.mozilla.com/D92958

gfx/layers/wr/WebRenderBridgeParent.cpp

@@ -1971,7 +1971,7 @@ void WebRenderBridgeParent::SetOMTASampleTime() {
 void WebRenderBridgeParent::CompositeIfNeeded() {
   if (mSkippedComposite) {
     mSkippedComposite = false;
-    CompositeToTarget(mSkippedCompositeId, nullptr, nullptr);
+    mCompositorScheduler->ScheduleComposition();
   }
 }
 
@@ -1999,7 +1999,6 @@ void WebRenderBridgeParent::CompositeToTarget(VsyncId aId,
       wr::RenderThread::Get()->TooManyPendingFrames(mApi->GetId())) {
     // Render thread is busy, try next time.
     mSkippedComposite = true;
-    mSkippedCompositeId = aId;
     ResetPreviousSampleTime();
 
     // Record that we skipped presenting a frame for

gfx/layers/wr/WebRenderBridgeParent.h

@@ -509,7 +509,6 @@ class WebRenderBridgeParent final : public PWebRenderBridgeParent,
   CompositionOpportunityId mCompositionOpportunityId;
   nsCString mInitError;
 
-  VsyncId mSkippedCompositeId;
   TimeStamp mMostRecentComposite;
 
 #if defined(MOZ_WIDGET_ANDROID)