Bug 1363958 - Fix WebRenderLayerManager::FlushRendering() r=nical

gfx/layers/ipc/CompositorBridgeParent.cpp

@@ -532,6 +532,11 @@ CompositorBridgeParent::RecvWaitOnTransactionProcessed()
 mozilla::ipc::IPCResult
 CompositorBridgeParent::RecvFlushRendering()
 {
+  if (gfxVars::UseWebRender()) {
+    mWrBridge->FlushRendering(/* aSync */ true);
+    return IPC_OK();
+  }
+
   if (mCompositorScheduler->NeedsComposite()) {
     CancelCurrentCompositeTask();
     ForceComposeToTarget(nullptr);
@@ -542,6 +547,11 @@ CompositorBridgeParent::RecvFlushRendering()
 mozilla::ipc::IPCResult
 CompositorBridgeParent::RecvFlushRenderingAsync()
 {
+  if (gfxVars::UseWebRender()) {
+    mWrBridge->FlushRendering(/* aSync */ false);
+    return IPC_OK();
+  }
+
   return RecvFlushRendering();
 }
 

gfx/layers/wr/WebRenderBridgeParent.cpp

@@ -123,7 +123,7 @@ WebRenderBridgeParent::WebRenderBridgeParent(CompositorBridgeParentBase* aCompos
   , mIdNameSpace(AllocIdNameSpace())
   , mPaused(false)
   , mDestroyed(false)
-  , mIsSnapshotting(false)
+  , mForceRendering(false)
 {
   MOZ_ASSERT(mCompositableHolder);
   mCompositableHolder->AddPipeline(mPipelineId);
@@ -618,7 +618,7 @@ WebRenderBridgeParent::RecvDPGetSnapshot(PTextureParent* aTexture)
   // Assert the stride of the buffer is what webrender expects
   MOZ_ASSERT((uint32_t)(size.width * 4) == stride);
 
-  mIsSnapshotting = true;
+  mForceRendering = true;
 
   if (mCompositorScheduler->NeedsComposite()) {
     mCompositorScheduler->CancelCurrentCompositeTask();
@@ -627,7 +627,7 @@ WebRenderBridgeParent::RecvDPGetSnapshot(PTextureParent* aTexture)
 
   mApi->Readback(size, buffer, buffer_size);
 
-  mIsSnapshotting = false;
+  mForceRendering = false;
 
   return IPC_OK();
 }
@@ -822,7 +822,7 @@ WebRenderBridgeParent::CompositeToTarget(gfx::DrawTarget* aTarget, const gfx::In
 
   const uint32_t maxPendingFrameCount = 2;
 
-  if (!mIsSnapshotting &&
+  if (!mForceRendering &&
       wr::RenderThread::Get()->GetPendingFrameCount(mApi->GetId()) > maxPendingFrameCount) {
     // Render thread is busy, try next time.
     ScheduleComposition();
@@ -938,6 +938,26 @@ WebRenderBridgeParent::ScheduleComposition()
   }
 }
 
+void
+WebRenderBridgeParent::FlushRendering(bool aIsSync)
+{
+  if (mDestroyed) {
+    return;
+  }
+
+  if (!mCompositorScheduler->NeedsComposite()) {
+    return;
+  }
+
+  mForceRendering = true;
+  mCompositorScheduler->CancelCurrentCompositeTask();
+  mCompositorScheduler->ForceComposeToTarget(nullptr, nullptr);
+  if (aIsSync) {
+    mApi->WaitFlushed();
+  }
+  mForceRendering = false;
+}
+
 void
 WebRenderBridgeParent::Pause()
 {

gfx/layers/wr/WebRenderBridgeParent.h

@@ -177,6 +177,8 @@ public:
     return ++sIdNameSpace;
   }
 
+  void FlushRendering(bool aIsSync);
+
 private:
   virtual ~WebRenderBridgeParent();
 
@@ -252,7 +254,7 @@ private:
 
   bool mPaused;
   bool mDestroyed;
-  bool mIsSnapshotting;
+  bool mForceRendering;
 
   // Can only be accessed on the compositor thread.
   WebRenderScrollData mScrollData;

gfx/layers/wr/WebRenderLayerManager.cpp

@@ -464,9 +464,16 @@ WebRenderLayerManager::RemoveDidCompositeObserver(DidCompositeObserver* aObserve
 void
 WebRenderLayerManager::FlushRendering()
 {
-  CompositorBridgeChild* bridge = GetCompositorBridgeChild();
-  if (bridge) {
-    bridge->SendFlushRendering();
+  CompositorBridgeChild* cBridge = GetCompositorBridgeChild();
+  if (!cBridge) {
+    return;
+  }
+  MOZ_ASSERT(mWidget);
+
+  if (mWidget->SynchronouslyRepaintOnResize() || gfxPrefs::LayersForceSynchronousResize()) {
+    cBridge->SendFlushRendering();
+  } else {
+    cBridge->SendFlushRenderingAsync();
   }
 }
 

gfx/webrender_bindings/WebRenderAPI.h

@@ -23,6 +23,7 @@ class CompositorWidget;
 
 namespace layers {
 class CompositorBridgeParentBase;
+class WebRenderBridgeParent;
 }
 
 namespace wr {
@@ -125,6 +126,7 @@ protected:
   bool mUseANGLE;
 
   friend class DisplayListBuilder;
+  friend class layers::WebRenderBridgeParent;
 };
 
 /// This is a simple C++ wrapper around WrState defined in the rust bindings.