Subclass GrVkCommandBuffer into Primary and Secondary CommandBuffers.

src/gpu/vk/GrVkRenderPass.h

Index: src/gpu/vk/GrVkRenderPass.h
diff --git a/src/gpu/vk/GrVkRenderPass.h b/src/gpu/vk/GrVkRenderPass.h
index 054f08e6a5ff766e1a6f8e8b19467fa72e975537..16bbf45e5721993b366e59d878c163d9e9711dda 100644
--- a/src/gpu/vk/GrVkRenderPass.h
+++ b/src/gpu/vk/GrVkRenderPass.h
@@ -115,6 +115,8 @@ public:
     // basic RenderPasses that can be used when creating a VkFrameBuffer object.
     bool isCompatible(const GrVkRenderTarget& target) const;
 
+    bool isCompatible(const GrVkRenderPass& renderPass) const;
+
     bool equalLoadStoreOps(const LoadStoreOps& colorOps,
                            const LoadStoreOps& resolveOps,
                            const LoadStoreOps& stencilOps) const;
@@ -131,6 +133,8 @@ private:
               const LoadStoreOps& resolveOps,
               const LoadStoreOps& stencilOps);
 
+    bool isCompatible(const AttachmentsDescriptor&, const AttachmentFlags&) const;
+
     void freeGPUData(const GrVkGpu* gpu) const override;
 
     VkRenderPass          fRenderPass;