Add caps and GL API for buffer texture

src/gpu/gl/GrGLCaps.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGLCaps.h"
 
@@ skipping 699 matching lines @@
     }
 
     if (glslCaps->fExternalTextureSupport) {
         if (ctxInfo.glslGeneration() == k110_GrGLSLGeneration) {
             glslCaps->fExternalTextureExtensionString = "GL_OES_EGL_image_external";
         } else {
             glslCaps->fExternalTextureExtensionString = "GL_OES_EGL_image_external_essl3";
         }
     }
 
+    if (kGL_GrGLStandard == standard) {
+        glslCaps->fBufferTextureSupport = ctxInfo.version() > GR_GL_VER(3, 1) &&
+                                          ctxInfo.glslGeneration() >= k330_GrGLSLGeneration;
+    } else {
+        if (ctxInfo.version() > GR_GL_VER(3, 2) &&
+            ctxInfo.glslGeneration() >= k320es_GrGLSLGeneration) {
+            glslCaps->fBufferTextureSupport = true;
+        } else if (ctxInfo.hasExtension("GL_OES_texture_buffer")) {
+            glslCaps->fBufferTextureSupport = true;
+            glslCaps->fBufferTextureExtensionString = "GL_OES_texture_buffer";
+        } else if (ctxInfo.hasExtension("GL_EXT_texture_buffer")) {
+            glslCaps->fBufferTextureSupport = true;
+            glslCaps->fBufferTextureExtensionString = "GL_EXT_texture_buffer";
+        }
+    }
+
     // The Tegra3 compiler will sometimes never return if we have min(abs(x), 1.0), so we must do
     // the abs first in a separate expression.
     if (kTegra3_GrGLRenderer == ctxInfo.renderer()) {
         glslCaps->fCanUseMinAndAbsTogether = false;
     }
 
     // On Intel GPU there is an issue where it reads the second argument to atan "- %s.x" as an int
     // thus must us -1.0 * %s.x to work correctly
     if (kIntel_GrGLVendor == ctxInfo.vendor()) {
         glslCaps->fMustForceNegatedAtanParamToFloat = true;
@@ skipping 1081 matching lines @@
         for (int j = 0; j < kExternalFormatUsageCnt; ++j) {
             SkASSERT(defaultEntry.fFormats.fExternalFormat[j] !=
                      fConfigTable[i].fFormats.fExternalFormat[j]);
         }
         SkASSERT(defaultEntry.fFormats.fExternalType != fConfigTable[i].fFormats.fExternalType);
     }
 #endif
 }
 
 void GrGLCaps::onApplyOptionsOverrides(const GrContextOptions& options) {}