Bug 1394337 - Fix uninitialized mPipelineId by WebRenderBridgeParent::CreateDestroyed() r=kats

WebRenderBridgeParent holds uninitialized mPipelineId when it was created by WebRenderBridgeParent::CreateDestroyed(). Then when CrossProcessCompositorBridgeParent::DeallocPWebRenderBridgeParent is called for the WebRenderBridgeParent, it will call EraseLayerState with some garbage uninitialized value, and so it will erase some random layer state entry.

gfx/layers/ipc/CompositorBridgeParent.cpp

@@ -1697,7 +1697,7 @@ CompositorBridgeParent::AllocPWebRenderBridgeParent(const wr::PipelineId& aPipel
   RefPtr<widget::CompositorWidget> widget = mWidget;
   RefPtr<wr::WebRenderAPI> api = wr::WebRenderAPI::Create(this, Move(widget), aSize);
   if (!api) {
-    mWrBridge = WebRenderBridgeParent::CreateDestroyed();
+    mWrBridge = WebRenderBridgeParent::CreateDestroyed(aPipelineId);
     mWrBridge.get()->AddRef(); // IPDL reference
     *aIdNamespace = mWrBridge->GetIdNamespace();
     *aTextureFactoryIdentifier = TextureFactoryIdentifier(LayersBackend::LAYERS_NONE);

gfx/layers/ipc/CrossProcessCompositorBridgeParent.cpp

@@ -217,7 +217,7 @@ CrossProcessCompositorBridgeParent::AllocPWebRenderBridgeParent(const wr::Pipeli
     // This could happen when this function is called after CompositorBridgeParent destruction.
     // This was observed during Tab move between different windows.
     NS_WARNING("Created child without a matching parent?");
-    parent = WebRenderBridgeParent::CreateDestroyed();
+    parent = WebRenderBridgeParent::CreateDestroyed(aPipelineId);
     parent->AddRef(); // IPDL reference
     *aIdNamespace = parent->GetIdNamespace();
     *aTextureFactoryIdentifier = TextureFactoryIdentifier(LayersBackend::LAYERS_NONE);

gfx/layers/wr/WebRenderBridgeParent.cpp

@@ -143,8 +143,9 @@ WebRenderBridgeParent::WebRenderBridgeParent(CompositorBridgeParentBase* aCompos
   }
 }
 
-WebRenderBridgeParent::WebRenderBridgeParent()
+WebRenderBridgeParent::WebRenderBridgeParent(const wr::PipelineId& aPipelineId)
   : mCompositorBridge(nullptr)
+  , mPipelineId(aPipelineId)
   , mChildLayerObserverEpoch(0)
   , mParentLayerObserverEpoch(0)
   , mWrEpoch(0)
@@ -156,9 +157,9 @@ WebRenderBridgeParent::WebRenderBridgeParent()
 }
 
 /* static */ WebRenderBridgeParent*
-WebRenderBridgeParent::CreateDestroyed()
+WebRenderBridgeParent::CreateDestroyed(const wr::PipelineId& aPipelineId)
 {
-  return new WebRenderBridgeParent();
+  return new WebRenderBridgeParent(aPipelineId);
 }
 
 WebRenderBridgeParent::~WebRenderBridgeParent()

gfx/layers/wr/WebRenderBridgeParent.h

@@ -55,7 +55,7 @@ public:
                         RefPtr<AsyncImagePipelineManager>&& aImageMgr,
                         RefPtr<CompositorAnimationStorage>&& aAnimStorage);
 
-  static WebRenderBridgeParent* CreateDestroyed();
+  static WebRenderBridgeParent* CreateDestroyed(const wr::PipelineId& aPipelineId);
 
   wr::PipelineId PipelineId() { return mPipelineId; }
   wr::WebRenderAPI* GetWebRenderAPI() { return mApi; }
@@ -198,7 +198,7 @@ public:
                        CompositorAnimationStorage* aAnimStorage);
 
 private:
-  WebRenderBridgeParent();
+  explicit WebRenderBridgeParent(const wr::PipelineId& aPipelineId);
   virtual ~WebRenderBridgeParent();
 
   uint64_t GetLayersId() const;