Add caps and GL API for buffer texture

src/gpu/gl/GrGLInterface.cpp

Index: src/gpu/gl/GrGLInterface.cpp
diff --git a/src/gpu/gl/GrGLInterface.cpp b/src/gpu/gl/GrGLInterface.cpp
index 84c51fb2524cc08a7ca85bee3a7f131265f95b77..728fb3f9e5f29e8d91e0a385eb328636d709454d 100644
--- a/src/gpu/gl/GrGLInterface.cpp
+++ b/src/gpu/gl/GrGLInterface.cpp
@@ -424,6 +424,21 @@ bool GrGLInterface::validate() const {
     }
 
     if (kGL_GrGLStandard == fStandard) {
+        if (glVer >= GR_GL_VER(3,1)) {
+            if (nullptr == fFunctions.fTexBuffer) {
+                RETURN_FALSE_INTERFACE;
+            }
+        }
+    } else {
+        if (glVer >= GR_GL_VER(3,2) || fExtensions.has("GL_OES_texture_buffer") ||
+            fExtensions.has("GL_EXT_texture_buffer")) {
+            if (nullptr == fFunctions.fTexBuffer) {
+                RETURN_FALSE_INTERFACE;
+            }
+        }
+    }
+
+    if (kGL_GrGLStandard == fStandard) {
         if (glVer >= GR_GL_VER(3, 0) || fExtensions.has("GL_ARB_vertex_array_object")) {
             if (nullptr == fFunctions.fBindVertexArray ||
                 nullptr == fFunctions.fDeleteVertexArrays ||
@@ -746,6 +761,11 @@ bool GrGLInterface::validate() const {
                 RETURN_FALSE_INTERFACE
             }
         }
+        if (glVer >= GR_GL_VER(3,1)) {
+            if (nullptr == fFunctions.fTextureBuffer) {
+                RETURN_FALSE_INTERFACE;
+            }
+        }
     }
 
     if ((kGL_GrGLStandard == fStandard && glVer >= GR_GL_VER(4,3)) ||