Mesa ES 3.0 requires sized internal formats

src/gpu/gl/GrGpuGL.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "GrGpuGL.h"
 #include "GrGLStencilBuffer.h"
@@ skipping 550 matching lines @@
     GrGLenum externalType = 0x0;// suprress warning
 
     // glTexStorage requires sized internal formats on both desktop and ES. ES2 requires an unsized
     // format for glTexImage, unlike ES3 and desktop. However, we allow the driver to decide the
     // size of the internal format whenever possible and so only use a sized internal format when
     // using texture storage.
     bool useSizedFormat = useTexStorage;
     // At least some versions of the ES3 drivers for NVIDIA and IMG won't accept GL_RED in
     // glTexImage2D for the internal format but will accept GL_R8.
     if (kNVIDIA_GrGLVendor == this->glContext().vendor() ||
-        kImagination_GrGLVendor == this->glContext().vendor()) {
+        kImagination_GrGLVendor == this->glContext().vendor() ||
+        this->glContext().isMesa()) {
         if (kGLES_GrGLStandard == this->glStandard() && this->glVersion() >= GR_GL_VER(3, 0) &&
             kAlpha_8_GrPixelConfig == dataConfig) {
            useSizedFormat = true;
         }
     }
     if (!this->configToGLFormats(dataConfig, useSizedFormat, &internalFormat,
                                  &externalFormat, &externalType)) {
         return false;
     }
 
@@ skipping 1974 matching lines @@
             this->setVertexArrayID(gpu, 0);
         }
         int attrCount = gpu->glCaps().maxVertexAttributes();
         if (fDefaultVertexArrayAttribState.count() != attrCount) {
             fDefaultVertexArrayAttribState.resize(attrCount);
         }
         attribState = &fDefaultVertexArrayAttribState;
     }
     return attribState;
 }