gpu: Avoid detaching images with glTexSubImage2D

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 6b254e0966bb8ad2de4ee746bf53e6f7cb3dc269..58a73597e541a4adeead8a33dea305a53996fc3b 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -8490,10 +8490,13 @@ bool GLES2DecoderImpl::ClearLevel(
   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(
@@ -9441,7 +9444,8 @@ error::Error GLES2DecoderImpl::DoTexSubImage2D(
   }
 
   if (!texture_state_.texsubimage2d_faster_than_teximage2d &&
-      !texture->IsImmutable()) {
+      !texture->IsImmutable() &&
+      !texture->HasImages()) {
     ScopedTextureUploadTimer timer(&texture_state_);
     GLenum internal_format;
     GLenum tex_type;