Revert "[translate] Add translate ranker model loader."

components/translate/core/browser/proto/ranker_model.proto

-// Copyright (c) 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-//
-// Experimental Translation Assist Model to allow/suppress translation prompts.
-
-syntax = "proto2";
-
-option optimize_for = LITE_RUNTIME;
-
-import "translate_ranker_model.proto";
-
-package chrome_intelligence;
-
-// Metadata for a ranker model instance. This data describes how the ranker
-// model should be interpreted/used.
-message RankerModelMetadata {
-  // An identifier denoting the type or purpose of this model.
-  optional string name = 1;
-
-  // An identifier denoting the specific instance of this model. For example:
-  // "Experiment B"
-  optional string label = 2;
-
-  // An identifier, typically a URL, denoting the source from which this model
-  // was obtained. The model referenced with a given source is presumed to be
-  // immutable; this can be used as a cache control mechanism. If the currently
-  // configured model source matches the source of a cached model, and the
-  // cached model has not expired then there is no need to refresh the model.
-  optional string source = 3;
-
-  // The timestamp at which this model was downloaded. This will be set by the
-  // model loader before it caches the model to disk.
-  optional int64 last_modified_sec = 4;
-
-  // The (optional) number of seconds after which this model should be
-  // considered expired. If the value is zero or not set, then the cached
-  // instance of the model never expires. A new download can be triggered by
-  // changing the configured source URL for the model loader.
-  optional int64 cache_duration_sec = 5;
-}
-
-// Defines an envelope/wrapper for general models.
-message RankerModelProto {
-  // Metadata.
-  optional RankerModelMetadata metadata = 1;
-
-  oneof model { TranslateRankerModel translate = 2; }
-}