Ignore calls to SatisfySequence if CanvasSurfaceLayerBridge is gone

third_party/WebKit/Source/platform/graphics/CanvasSurfaceLayerBridge.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/CanvasSurfaceLayerBridge.h"
 
 #include "cc/layers/layer.h"
 #include "cc/layers/solid_color_layer.h"
 #include "cc/layers/surface_layer.h"
 #include "cc/surfaces/sequence_surface_reference_factory.h"
@@ skipping 26 matching lines @@
   ~OffscreenCanvasSurfaceReferenceFactory() override = default;
 
   // cc::SequenceSurfaceReferenceFactory implementation:
   void RequireSequence(const cc::SurfaceId& id,
                        const cc::SurfaceSequence& sequence) const override {
     DCHECK(bridge_);
     bridge_->RequireCallback(id, sequence);
   }
 
   void SatisfySequence(const cc::SurfaceSequence& sequence) const override {
-    DCHECK(bridge_);
-    bridge_->SatisfyCallback(sequence);
+    if (bridge_)
+      bridge_->SatisfyCallback(sequence);

[Fady Samuel, 2017/05/26 20:47:57]

maybe do this for require too?

[Saman Sami, 2017/05/29 17:48:22]

I expect bridge_ to exist in RequireSequence. SatisfySequence is PostTasked so
lifetimes get messed up.

   }
 
   base::WeakPtr<CanvasSurfaceLayerBridge> bridge_;
 
   DISALLOW_COPY_AND_ASSIGN(OffscreenCanvasSurfaceReferenceFactory);
 };
 
 }  // namespace
 
 CanvasSurfaceLayerBridge::CanvasSurfaceLayerBridge(
@@ skipping 67 matching lines @@
   service_->Satisfy(sequence);
 }
 
 void CanvasSurfaceLayerBridge::RequireCallback(
     const cc::SurfaceId& surface_id,
     const cc::SurfaceSequence& sequence) {
   service_->Require(surface_id, sequence);
 }
 
 }  // namespace blink