cc: Make one-copy tile initialization mechanism use immutable textures.

ui/gl/gl_image_memory.cc

 // Copyright 2014 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 "ui/gl/gl_image_memory.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/scoped_binders.h"
@@ skipping 161 matching lines @@
 }
 
 bool GLImageMemory::CopyTexImage(unsigned target) {
   TRACE_EVENT0("gpu", "GLImageMemory::CopyTexImage");
 
   // GL_TEXTURE_EXTERNAL_OES is not a supported CopyTexImage target.
   if (target == GL_TEXTURE_EXTERNAL_OES)
     return false;
 
   DCHECK(memory_);
-  glTexImage2D(target,
-               0,  // mip level
-               TextureFormat(format_),
-               size_.width(),
-               size_.height(),
-               0,  // border
-               DataFormat(format_),
-               DataType(format_),
-               memory_);
+  glTexSubImage2D(target, 0 /* level */, 0 /* x */, 0 /* y */, size_.width(),
+                  size_.height(), DataFormat(format_), DataType(format_),
+                  memory_);

[dshwang, 2014/11/20 16:58:39]

glTexImage2D isn't allowed after calling glTexStorage2D.
In addition we can use glTexSubImage2D safely because
GLES2DecoderImpl::DoCopyTextureCHROMIUM makes sure the bound texture is already
allocated.
https://code.google.com/p/chromium/codesearch#chromium/src/gpu/command_buffer...

 
   return true;
 }
 
 void GLImageMemory::WillUseTexImage() {
   DCHECK(!in_use_);
   in_use_ = true;
 
   if (!need_do_bind_tex_image_)
     return;
@@ skipping 83 matching lines @@
                TextureFormat(format_),
                size_.width(),
                size_.height(),
                0,  // border
                DataFormat(format_),
                DataType(format_),
                memory_);
 }
 
 }  // namespace gfx