Implement helper functionalities for computing image size with ES3 settings.

gpu/command_buffer/service/context_state.cc

Index: gpu/command_buffer/service/context_state.cc
diff --git a/gpu/command_buffer/service/context_state.cc b/gpu/command_buffer/service/context_state.cc
index 44ad3199c1de5b3af3634baa38e2ad420d25b8f1..023d732c5cb492c383287d4eed381587ac819194 100644
--- a/gpu/command_buffer/service/context_state.cc
+++ b/gpu/command_buffer/service/context_state.cc
@@ -585,6 +585,28 @@ void ContextState::UnbindTexture(TextureRef* texture) {
   }
 }
 
+PixelStoreParams ContextState::GetPackParams() {
+  PixelStoreParams params;
+  params.alignment = pack_alignment;
+  params.row_length = pack_row_length;
+  params.skip_pixels = pack_skip_pixels;
+  params.skip_rows = pack_skip_rows;
+  return params;
+}
+
+PixelStoreParams ContextState::GetUnpackParams(Dimension dimension) {
+  PixelStoreParams params;
+  params.alignment = unpack_alignment;
+  params.row_length = unpack_row_length;
+  params.skip_pixels = unpack_skip_pixels;
+  params.skip_rows = unpack_skip_rows;
+  if (dimension == k3D) {
+    params.image_height = unpack_image_height;
+    params.skip_images = unpack_skip_images;
+  }
+  return params;
+}
+
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.