Consolidate GPU buffer implementations

Consolidates all the different buffer implementations into a single
GrBuffer class. This will allow us to add new buffer types, use DSA in
OpenGL, track buffer bindings by unique ID, cache buffers without
respect to the type of data they have been used for previously, etc.
This change is strictly a refactor; it introduces no change in
functionality.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1825393002

Committed: https://skia.googlesource.com/skia/+/8b1bff29675afd25843439eade634a57f68fe16f

Review URL: https://codereview.chromium.org/1825393002
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index 177fbab..35c04ca 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -8,10 +8,10 @@
 
 #include "GrGpu.h"
 
+#include "GrBuffer.h"
 #include "GrCaps.h"
 #include "GrContext.h"
 #include "GrGpuResourcePriv.h"
-#include "GrIndexBuffer.h"
 #include "GrMesh.h"
 #include "GrPathRendering.h"
 #include "GrPipeline.h"
@@ -20,8 +20,6 @@
 #include "GrRenderTargetPriv.h"
 #include "GrStencilAttachment.h"
 #include "GrSurfacePriv.h"
-#include "GrTransferBuffer.h"
-#include "GrVertexBuffer.h"
 #include "SkTypes.h"
 
 GrMesh& GrMesh::operator =(const GrMesh& di) {
@@ -238,28 +236,13 @@
     return this->onWrapBackendTextureAsRenderTarget(desc, ownership);
 }
 
-GrVertexBuffer* GrGpu::createVertexBuffer(size_t size, bool dynamic) {
+GrBuffer* GrGpu::createBuffer(GrBufferType type, size_t size, GrAccessPattern accessPattern) {
     this->handleDirtyContext();
-    GrVertexBuffer* vb = this->onCreateVertexBuffer(size, dynamic);
+    GrBuffer* buffer = this->onCreateBuffer(type, size, accessPattern);
     if (!this->caps()->reuseScratchBuffers()) {
-        vb->resourcePriv().removeScratchKey();
+        buffer->resourcePriv().removeScratchKey();
     }
-    return vb;
-}
-
-GrIndexBuffer* GrGpu::createIndexBuffer(size_t size, bool dynamic) {
-    this->handleDirtyContext();
-    GrIndexBuffer* ib = this->onCreateIndexBuffer(size, dynamic);
-    if (!this->caps()->reuseScratchBuffers()) {
-        ib->resourcePriv().removeScratchKey();
-    }
-    return ib;
-}
-
-GrTransferBuffer* GrGpu::createTransferBuffer(size_t size, TransferType type) {
-    this->handleDirtyContext();
-    GrTransferBuffer* tb = this->onCreateTransferBuffer(size, type);
-    return tb;
+    return buffer;
 }
 
 void GrGpu::clear(const SkIRect& rect,
@@ -416,13 +399,13 @@
 
 bool GrGpu::transferPixels(GrSurface* surface,
                            int left, int top, int width, int height,
-                           GrPixelConfig config, GrTransferBuffer* buffer,
+                           GrPixelConfig config, GrBuffer* transferBuffer,
                            size_t offset, size_t rowBytes) {
-    SkASSERT(buffer);
+    SkASSERT(transferBuffer);
 
     this->handleDirtyContext();
     if (this->onTransferPixels(surface, left, top, width, height, config,
-                               buffer, offset, rowBytes)) {
+                               transferBuffer, offset, rowBytes)) {
         fStats.incTransfersToTexture();
         return true;
     }