gpu: fix CopyTextureCHROMIUM for immutable texture.

gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc

Index: gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc b/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
index ffb9370bca76f071a1a3619a96e9a858007bafda..3e26f12e0e78c8ab81969ba6ce07d577340ed8df 100644
--- a/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
+++ b/gpu/command_buffer/service/gles2_cmd_copy_texture_chromium.cc
@@ -334,7 +334,9 @@ void CopyTextureCHROMIUMResourceManager::DoCopyTexture(
       (source_internal_format == GL_RGBA && dest_internal_format == GL_RGB);
   // GL_TEXTURE_RECTANGLE_ARB on FBO is supported by OpenGL, not GLES2,
   // so restrict this to GL_TEXTURE_2D.
-  if (source_target == GL_TEXTURE_2D && !flip_y && !premultiply_alpha_change &&
+  if ((source_target == GL_TEXTURE_2D ||
+       source_target == GL_TEXTURE_RECTANGLE_ARB) &&
+      !flip_y && !premultiply_alpha_change &&
       source_format_contain_superset_of_dest_format) {
     DoCopyTexImage2D(decoder,
                      source_target,