Add GpuCommandBuffer support.

src/gpu/vk/GrVkCommandBuffer.cpp

Index: src/gpu/vk/GrVkCommandBuffer.cpp
diff --git a/src/gpu/vk/GrVkCommandBuffer.cpp b/src/gpu/vk/GrVkCommandBuffer.cpp
index 9604355aad2bf5a388897f1afacff0d77280af0a..2b636edf20e6f68fdbe58eb2cf1e727c13ad3bd3 100644
--- a/src/gpu/vk/GrVkCommandBuffer.cpp
+++ b/src/gpu/vk/GrVkCommandBuffer.cpp
@@ -311,6 +311,9 @@ void GrVkPrimaryCommandBuffer::executeCommands(const GrVkGpu* gpu,
 
     GR_VK_CALL(gpu->vkInterface(), CmdExecuteCommands(fCmdBuffer, 1, &buffer->fCmdBuffer));
     this->addResource(buffer);
+    // When executing a secondary command buffer all state (besides render pass state) becomes
+    // invalidated and must be reset. This includes bound buffers, pipelines, dynamic state, etc.
+    this->invalidateState();

[jvanverth1, 2016/06/06 20:47:43]

All of it must be reset? That's unfortunate.

[egdaniel, 2016/06/07 15:22:37]

Yes. But in general this shouldn't hurt us because we'll hopefully already
merged draws together there were using the same pipeline, buffers, etc. So in
practice we were going to bind new things anyways.

 }
 
 void GrVkPrimaryCommandBuffer::submitToQueue(const GrVkGpu* gpu,