gpu: Refactor to support cross-channel shared textures

gpu/command_buffer/service/context_state.h

Index: gpu/command_buffer/service/context_state.h
diff --git a/gpu/command_buffer/service/context_state.h b/gpu/command_buffer/service/context_state.h
index af43eac45181b2e377016562069144ce48b160a6..e2bc012169eaa381089f6096e9d39185af4b90cf 100644
--- a/gpu/command_buffer/service/context_state.h
+++ b/gpu/command_buffer/service/context_state.h
@@ -36,21 +36,21 @@ struct GPU_EXPORT TextureUnit {
   GLenum bind_target;
 
   // texture currently bound to this unit's GL_TEXTURE_2D with glBindTexture
-  scoped_refptr<Texture> bound_texture_2d;
+  scoped_refptr<TextureRef> bound_texture_2d;
 
   // texture currently bound to this unit's GL_TEXTURE_CUBE_MAP with
   // glBindTexture
-  scoped_refptr<Texture> bound_texture_cube_map;
+  scoped_refptr<TextureRef> bound_texture_cube_map;
 
   // texture currently bound to this unit's GL_TEXTURE_EXTERNAL_OES with
   // glBindTexture
-  scoped_refptr<Texture> bound_texture_external_oes;
+  scoped_refptr<TextureRef> bound_texture_external_oes;
 
   // texture currently bound to this unit's GL_TEXTURE_RECTANGLE_ARB with
   // glBindTexture
-  scoped_refptr<Texture> bound_texture_rectangle_arb;
+  scoped_refptr<TextureRef> bound_texture_rectangle_arb;
 
-  scoped_refptr<Texture> GetInfoForSamplerType(
+  scoped_refptr<TextureRef> GetInfoForSamplerType(
       GLenum type) {
     DCHECK(type == GL_SAMPLER_2D || type == GL_SAMPLER_CUBE ||
            type == GL_SAMPLER_EXTERNAL_OES || type == GL_SAMPLER_2D_RECT_ARB);
@@ -69,7 +69,7 @@ struct GPU_EXPORT TextureUnit {
     return NULL;
   }
 
-  void Unbind(Texture* texture) {
+  void Unbind(TextureRef* texture) {
     if (bound_texture_2d == texture) {
       bound_texture_2d = NULL;
     }