Create free list heap for suballocation

src/gpu/vk/GrVkGpu.h

Index: src/gpu/vk/GrVkGpu.h
diff --git a/src/gpu/vk/GrVkGpu.h b/src/gpu/vk/GrVkGpu.h
index cd72c69bd472078aa75c2c81568f0ae40b5f4b78..6269ede45c63c175f04ad870e4d1c0240fdc3bf0 100644
--- a/src/gpu/vk/GrVkGpu.h
+++ b/src/gpu/vk/GrVkGpu.h
@@ -13,6 +13,7 @@
 #include "vk/GrVkBackendContext.h"
 #include "GrVkCaps.h"
 #include "GrVkIndexBuffer.h"
+#include "GrVkMemory.h"
 #include "GrVkResourceProvider.h"
 #include "GrVkVertexBuffer.h"
 #include "GrVkUtil.h"
@@ -122,6 +123,23 @@ public:
 
     void generateMipmap(GrVkTexture* tex) const;
 
+    // Heaps
+    enum Heap {
+        kLinearImage_Heap = 0,
+        kOptimalImage_Heap,
+        kSmallOptimalImage_Heap,
+        kVertexBuffer_Heap,

[bsalomon, 2016/06/10 15:14:53]

Why separate index and vertex heaps? What's the optimal vs small optimal
distinction?

[jvanverth1, 2016/06/10 15:41:20]

I'll add some comments. In Vulkan, the index of the heap depends on the buffer
type. So in theory, a driver's implementation could have different heaps for
index and vertex buffers. The small vs. non-small distinction is to reduce
fragmentation in the texture heap. 

[jvanverth1, 2016/06/10 18:31:55]

As a side note, I'd like to incorporate the small-large distinction within the
heap (I think malloc does something similar), but would rather do that as a
separate change.

[jvanverth1, 2016/06/13 19:59:22]

Done.

+        kIndexBuffer_Heap,
+        kUniformBuffer_Heap,
+        kCopyReadBuffer_Heap,
+        kCopyWriteBuffer_Heap,
+
+        kLastHeap = kCopyWriteBuffer_Heap
+    };
+    static const int kHeapCount = kLastHeap + 1;
+
+    GrVkHeap* getHeap(Heap heap) const { return fHeaps[heap]; }
+
 private:
     GrVkGpu(GrContext* context, const GrContextOptions& options,
             const GrVkBackendContext* backendContext);
@@ -226,6 +244,8 @@ private:
     GrVkPrimaryCommandBuffer*              fCurrentCmdBuffer;
     VkPhysicalDeviceMemoryProperties       fPhysDevMemProps;
 
+    GrVkHeap*                             fHeaps[kHeapCount];
+
 #ifdef ENABLE_VK_LAYERS
     // For reporting validation layer errors
     VkDebugReportCallbackEXT               fCallback;