Set the texture base level before generating sRGB mipmaps.

gpu/command_buffer/service/gles2_cmd_srgb_converter.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_srgb_converter.h"
 
 #include "gpu/command_buffer/service/texture_manager.h"
 #include "ui/gl/gl_version_info.h"
 
 namespace {
@@ skipping 460 matching lines @@
   glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER, srgb_encoder_fbo_);
   glBindTexture(GL_TEXTURE_2D, srgb_converter_textures_[1]);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
                   GL_NEAREST_MIPMAP_NEAREST);
 
   width = (width == 1) ? 1 : width >> 1;
   height = (height == 1) ? 1 : height >> 1;
 
   base::CheckedNumeric<GLint> level = base_level;
   level += 1;
-  for (; level.IsValid() && level.ValueOrDie() <= max_mipmap_available_level;
-       ++level) {
+
+  if (!tex->IsImmutable()) {
+    glBindTexture(GL_TEXTURE_2D, tex->service_id());
+    GLsizei level_width = width;
+    GLsizei level_height = height;
+    for (base::CheckedNumeric<GLint> i = level;
+         i.IsValid() && i.ValueOrDie() <= max_mipmap_available_level; ++i) {
+      glTexImage2D(GL_TEXTURE_2D, i.ValueOrDie(), internal_format, level_width,
+                   level_height, 0, format, type, nullptr);
+      level_width = (level_width == 1) ? 1 : level_width >> 1;
+      level_height = (level_height == 1) ? 1 : level_height >> 1;
+    }
+  }
+
+  glBindTexture(GL_TEXTURE_2D, srgb_converter_textures_[1]);
+  for (base::CheckedNumeric<GLint> i = level;
+       i.IsValid() && i.ValueOrDie() <= max_mipmap_available_level; ++i) {
     // copy mipmaps level by level from srgb_converter_textures_[1] to tex
     // generate mipmap for tex manually
-    glBindTexture(GL_TEXTURE_2D, tex->service_id());
-    if (!tex->IsImmutable()) {
-      glTexImage2D(GL_TEXTURE_2D, level.ValueOrDie(), internal_format, width,
-                   height, 0, format, type, nullptr);
-    }
     glFramebufferTexture2DEXT(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
-                              GL_TEXTURE_2D, tex->service_id(),
-                              level.ValueOrDie());
+                              GL_TEXTURE_2D, tex->service_id(), i.ValueOrDie());
 
-    glBindTexture(GL_TEXTURE_2D, srgb_converter_textures_[1]);
+    DCHECK_EQ(static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE),
+              glCheckFramebufferStatusEXT(GL_DRAW_FRAMEBUFFER));
+
     glViewport(0, 0, width, height);
     glDrawArrays(GL_TRIANGLES, 0, 6);
     width = (width == 1) ? 1 : width >> 1;
     height = (height == 1) ? 1 : height >> 1;
   }
 
   // Restore state
   decoder->RestoreAllAttributes();
   decoder->RestoreTextureUnitBindings(0);
   decoder->RestoreActiveTexture();
   decoder->RestoreProgramBindings();
   decoder->RestoreBufferBindings();
   decoder->RestoreFramebufferBindings();
   decoder->RestoreGlobalState();
   decoder->RestoreTextureState(tex->service_id());
 }
 
 }  // namespace gles2.
 }  // namespace gpu