Allow creating GLImage-backed textures with glTexStorage2D.

gpu/command_buffer/service/texture_manager.h

Index: gpu/command_buffer/service/texture_manager.h
diff --git a/gpu/command_buffer/service/texture_manager.h b/gpu/command_buffer/service/texture_manager.h
index 02c5c1119c781cf6a62d236fcfe521d00ac3ceef..da7c26212e0e0e48546bec7670a0306de6c5e791 100644
--- a/gpu/command_buffer/service/texture_manager.h
+++ b/gpu/command_buffer/service/texture_manager.h
@@ -159,6 +159,8 @@ class GPU_EXPORT Texture final : public TextureBase {
     return usage_;
   }
 
+  GLint buffer_usage() const { return buffer_usage_; }
+
   GLenum compare_func() const {
     return sampler_state_.compare_func;
   }
@@ -606,6 +608,7 @@ class GPU_EXPORT Texture final : public TextureBase {
   GLenum swizzle_g_;
   GLenum swizzle_b_;
   GLenum swizzle_a_;
+  GLint buffer_usage_ = GL_NONE;
 
   // The maximum level that has been set.
   GLint max_level_set_;