Don't create new descriptor set for vulkan uniforms every draw

src/gpu/vk/GrVkPipelineState.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "GrVkPipelineState.h"
 
 #include "GrPipeline.h"
@@ skipping 182 matching lines @@
     fXferProcessor->setData(fDataManager, pipeline.getXferProcessor());
     append_texture_bindings(pipeline.getXferProcessor(), &textureBindings);
 
     // Get new descriptor sets
     if (fNumSamplers) {
         fSamplerPoolManager.getNewDescriptorSet(gpu,
                                              &fDescriptorSets[GrVkUniformHandler::kSamplerDescSet]);
         this->writeSamplers(gpu, textureBindings);
     }
 
-
     if (fVertexUniformBuffer.get() || fFragmentUniformBuffer.get()) {
-        fUniformPoolManager.getNewDescriptorSet(gpu,
+        if (fDataManager.uploadUniformBuffers(gpu, fVertexUniformBuffer, fFragmentUniformBuffer) ||
+            VK_NULL_HANDLE == fDescriptorSets[GrVkUniformHandler::kUniformBufferDescSet]) {
+            fUniformPoolManager.getNewDescriptorSet(gpu,
                                        &fDescriptorSets[GrVkUniformHandler::kUniformBufferDescSet]);
-        this->writeUniformBuffers(gpu);
+            this->writeUniformBuffers(gpu);
+        }
     }
 }
 
 void GrVkPipelineState::writeUniformBuffers(const GrVkGpu* gpu) {
-    fDataManager.uploadUniformBuffers(gpu, fVertexUniformBuffer, fFragmentUniformBuffer);
-
     VkWriteDescriptorSet descriptorWrites[2];
     memset(descriptorWrites, 0, 2 * sizeof(VkWriteDescriptorSet));
 
     uint32_t firstUniformWrite = 0;
     uint32_t uniformBindingUpdateCount = 0;
 
     VkDescriptorBufferInfo vertBufferInfo;
     // Vertex Uniform Buffer
     if (fVertexUniformBuffer.get()) {
         ++uniformBindingUpdateCount;
@@ skipping 277 matching lines @@
 
     b.add32(get_blend_info_key(pipeline));
 
     b.add32(primitiveType);
 
     // Set key length
     int keyLength = key->count();
     SkASSERT(0 == (keyLength % 4));
     *reinterpret_cast<uint32_t*>(key->begin()) = SkToU32(keyLength);
 }