Add GpuCommandBuffer support.

src/gpu/gl/GrGLGpu.cpp

Index: src/gpu/gl/GrGLGpu.cpp
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index 8aec4d684dc9ae9f0b019f862b900cac4dd42d64..3d39220e41be4e0382c079c224e9eb4edc28a2c6 100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -8,6 +8,7 @@
 #include "GrGLGpu.h"
 #include "GrGLBuffer.h"
 #include "GrGLGLSL.h"
+#include "GrGLGpuCommandBuffer.h"
 #include "GrGLStencilAttachment.h"
 #include "GrGLTextureRenderTarget.h"
 #include "GrGpuResourcePriv.h"
@@ -2623,6 +2624,14 @@ bool GrGLGpu::onReadPixels(GrSurface* surface,
     return true;
 }
 
+GrGpuCommandBuffer* GrGLGpu::createCommandBuffer(const GrRenderTarget& target,
+                                                 GrGpuCommandBuffer::LoadAndStoreOp colorOp,
+                                                 GrColor colorClear,
+                                                 GrGpuCommandBuffer::LoadAndStoreOp stencilOp,
+                                                 GrColor stencilClear) {
+    return new GrGLGpuCommandBuffer(this);
+}
+
 void GrGLGpu::finishDrawTarget() {
     if (fPLSHasBeenUsed) {
         /* There is an ARM driver bug where if we use PLS, and then draw a frame which does not