Track GL buffer state based on unique resource ID

src/gpu/GrResourceProvider.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrResourceProvider_DEFINED
 #define GrResourceProvider_DEFINED
 
@@ skipping 84 matching lines @@
     enum Flags {
         /** If the caller intends to do direct reads/writes to/from the CPU then this flag must be
          *  set when accessing resources during a GrDrawTarget flush. This includes the execution of
          *  GrBatch objects. The reason is that these memory operations are done immediately and
          *  will occur out of order WRT the operations being flushed.
          *  Make this automatic: https://bug.skia.org/4156
          */
         kNoPendingIO_Flag = kNoPendingIO_ScratchTextureFlag,
     };
 
-    GrBuffer* createBuffer(GrBufferType, size_t size, GrAccessPattern, uint32_t flags);
+    /**
+     * Returns a buffer.
+     *
+     * @param size            minimum size of buffer to return.
+     * @param intendedType    hint to the graphics subsystem about what the buffer will be used for.
+     * @param GrAccessPattern hint to the graphics subsystem about how the data will be accessed.
+     * @param flags           see Flags enum.
+     *
+     * @return the buffer if successful, otherwise nullptr.
+     */
+    GrBuffer* createBuffer(size_t size, GrBufferType intendedType, GrAccessPattern, uint32_t flags);
 
     GrTexture* createApproxTexture(const GrSurfaceDesc& desc, uint32_t flags) {
         SkASSERT(0 == flags || kNoPendingIO_Flag == flags);
         return this->internalCreateApproxTexture(desc, flags);
     }
 
     /**  Returns a GrBatchAtlas. This function can be called anywhere, but the returned atlas should
      *   only be used inside of GrBatch::generateGeometry
      *   @param GrPixelConfig    The pixel config which this atlas will store
      *   @param width            width in pixels of the atlas
@@ skipping 39 matching lines @@
                                                const GrUniqueKey& key);
 
     const GrBuffer* createQuadIndexBuffer();
 
     GrUniqueKey fQuadIndexBufferKey;
 
     typedef GrTextureProvider INHERITED;
 };
 
 #endif