Unify DescriptorPools for vulkan uniform descriptor sets

src/gpu/vk/GrVkResourceProvider.h

Index: src/gpu/vk/GrVkResourceProvider.h
diff --git a/src/gpu/vk/GrVkResourceProvider.h b/src/gpu/vk/GrVkResourceProvider.h
index 4853bf160c9ad4ab62b6775d7ef520d9376368ce..812146dab11a97f2659c0391c1ff5fe4bd3ece63 100644
--- a/src/gpu/vk/GrVkResourceProvider.h
+++ b/src/gpu/vk/GrVkResourceProvider.h
@@ -70,6 +70,18 @@ public:
                                                                  GrPrimitiveType,
                                                                  const GrVkRenderPass& renderPass);
 
+    // For all our GrVkPipelineState objects, we require a layout where the first set contains two
+    // uniform buffers, one for the vertex shader and one for the fragment shader. Thus it is
+    // possible for us to use a shadered descriptor pool to allocate all these similar descriptor
+    // sets. The caller is responsible for reffing the outPool for as long as the returned
+    // VkDescriptor set is in use.
+    void getUniformDescriptorSet(VkDescriptorSet*, const GrVkDescriptorPool** outPool);
+
+    // Returns the compatible VkDescriptorSetLayout to use for uniform buffers. The caller does not
+    // own the VkDescriptorSetLayout and thus should not delete it. This function should be used
+    // when the caller needs the layout to create a VkPipelineLayout.
+    VkDescriptorSetLayout getUniDSLayout() const { return fUniformDescLayout; }
+
     // Destroy any cached resources. To be called before destroying the VkDevice.
     // The assumption is that all queues are idle and all command buffers are finished.
     // For resource tracing to work properly, this should be called after unrefing all other
@@ -122,6 +134,9 @@ private:
 #endif
     };
 
+    // Initialiaze the vkDescriptorSetLayout used for allocating new uniform buffer descritpor sets.
+    void initUniformDescObjects();
+
     GrVkGpu* fGpu;
 
     // Central cache for creating pipelines
@@ -140,6 +155,15 @@ private:
 
     // Cache of GrVkPipelineStates
     PipelineStateCache* fPipelineStateCache;
+
+    // Current pool to allocate uniform descriptor sets from
+    const GrVkDescriptorPool* fUniformDescPool;
+    VkDescriptorSetLayout  fUniformDescLayout;
+    //Curent number of uniform descriptors allocated from the pool
+    int                fCurrentUniformDescCount;
+    int                fCurrMaxUniDescriptors;
+    static const int   kMaxUniformDescriptors = 1024;

[jvanverth1, 2016/04/28 20:34:30]

I believe that Chrome would prefer that these be enums rather than initialized
in the header. See the "static const members vs enums" discussion in
chromium-dev.

+    static const int   kNumUniformDescPerSet = 2;
 };
 
 #endif