Fix crash in 2D canvas caused by failed GPU context restoration

third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.cpp

Index: third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.cpp b/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.cpp
index cd0597a630fbc83d0f56d18d8cca82badeb58d4c..f5905c5a7960f6ab6ee9d91051f97c5e4695d3db 100644
--- a/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.cpp
+++ b/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.cpp
@@ -923,8 +923,9 @@ bool Canvas2DLayerBridge::PrepareTextureMailbox(
   // If the context is lost, we don't know if we should be producing GPU or
   // software frames, until we get a new context, since the compositor will
   // be trying to get a new context and may change modes.
-  if (m_contextProvider->contextGL()->GetGraphicsResetStatusKHR() !=
-      GL_NO_ERROR)
+  if (!m_contextProvider ||
+      m_contextProvider->contextGL()->GetGraphicsResetStatusKHR() !=
+          GL_NO_ERROR)
     return false;
 
   sk_sp<SkImage> image =