gpu: Avoid detaching images with glTexSubImage2D

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 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_decoder.h"
 
 #include <stdio.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 8472 matching lines @@
     }
   } else {
     tile_height = height;
   }
 
   // Assumes the size has already been checked.
   scoped_ptr<char[]> zero(new char[size]);
   memset(zero.get(), 0, size);
   glBindTexture(bind_target, service_id);
 
+  Texture* clear_texture =
+      texture_manager()->GetTextureForServiceId(service_id);

[no sievers, 2015/02/25 01:23:27]

Can you change it instead to pass in texture?
And then just do texture->service_id() wherever it needs that in here.

+  bool has_images = clear_texture && clear_texture->HasImages();
   GLint y = 0;
   while (y < height) {
     GLint h = y + tile_height > height ? height - y : tile_height;
-    if (is_texture_immutable || h != height) {
+    if (is_texture_immutable || h != height || has_images) {
       glTexSubImage2D(target, level, 0, y, width, h, format, type, zero.get());
     } else {
       glTexImage2D(
           target, level, internal_format, width, h, 0, format, type,
           zero.get());
     }
     y += tile_height;
   }
   TextureRef* texture = texture_manager()->GetTextureInfoForTarget(
       &state_, bind_target);
@@ skipping 927 matching lines @@
           GL_OUT_OF_MEMORY, "glTexSubImage2D", "dimensions too big");
       return error::kNoError;
     }
     ScopedTextureUploadTimer timer(&texture_state_);
     glTexSubImage2D(
         target, level, xoffset, yoffset, width, height, format, type, data);
     return error::kNoError;
   }
 
   if (!texture_state_.texsubimage2d_faster_than_teximage2d &&
-      !texture->IsImmutable()) {
+      !texture->IsImmutable() &&
+      !texture->HasImages()) {
     ScopedTextureUploadTimer timer(&texture_state_);
     GLenum internal_format;
     GLenum tex_type;
     texture->GetLevelType(target, level, &tex_type, &internal_format);
     // NOTE: In OpenGL ES 2.0 border is always zero. If that changes we'll need
     // to look it up.
     glTexImage2D(
         target, level, internal_format, width, height, 0, format, type, data);
   } else {
     ScopedTextureUploadTimer timer(&texture_state_);
@@ skipping 2666 matching lines @@
   }
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu