Merging proto changes.

This includes the following changes:
https://chromium.googlesource.com/feed/+/39fe4a79d4144e2e1eb170a7ba0a49b7510162f8

Change-Id: I462cf19eef5374e8aad4bc4b203e1fba03f73f73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2018142Reviewed-by: Dan H <harringtond@chromium.org>
Commit-Queue: Jonathan Freed <freedjm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734619}

chrome/android/feed/merging.md

@@ -4,4 +4,4 @@
 and [feed wire protos](https://cs.chromium.org/chromium/src/components/feed/core/proto/wire/)
 are hand-merged from https://chromium.googlesource.com/feed regularly.
 
-Last merged Change-Id: ebe07f69fec6980ee571771edd0d7ddf0c721880
+Last merged commit ID: 39fe4a79d4144e2e1eb170a7ba0a49b7510162f8

components/feed/core/proto/ui/piet/errors.proto

@@ -122,6 +122,17 @@ enum ErrorCode {
   // Fields start at ID 1.
   // ---------------------------------------------------------------------------
 
+  // When the client tries to reference a SharedState that is not found, the
+  // Frame cannot be rendered, and likely no frames can be rendered.
+  // This error code must be reported by the Piet host app, as the Piet
+  // implementation assumes that all shared states have been provided already.
+  ERR_MISSING_SHARED_STATE = 12 /* [
+    // Something is seriously wrong if a SharedState is missing
+    (server_error) = FATAL,
+    // Clients cannot render any Frame when SharedState is missing (no Template)
+    (client_error) = FATAL
+  ] */;
+
   // When a Template cannot be located, it only affects Frames that reference
   // it, so we can proceed to render other unaffected Frames, making this an
   // ERROR, not FATAL.