Adding client version of the models proto.

This change adds the proto elements for the Optimization Guide
Prediction System. It is used for model storage, requesting
updates from the remote OptimizationGuideService, and evaluating
models on the client.

This proto also contains the model definitions for ensembles and
decision trees that will be supported in v1 of the Optimization Guide
Prediction System. These are forked versions of the TensorFlow protos
for these elements.

Bug: 1001194
Change-Id: Ifddddb032076af98b4b0838a9d309f37e1322732
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1815228
Commit-Queue: Michael Crouse <mcrouse@chromium.org>
Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Reviewed-by: Doug Arnett <dougarnett@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698940}

components/optimization_guide/proto/BUILD.gn

@@ -9,6 +9,7 @@ proto_library("optimization_guide_proto") {
     "common_types.proto",
     "hint_cache.proto",
     "hints.proto",
+    "models.proto",
     "previews_metadata.proto",
   ]
 }

components/optimization_guide/proto/common_types.proto

@@ -36,3 +36,14 @@ enum EffectiveConnectionType {
   // 4G connection.
   EFFECTIVE_CONNECTION_TYPE_4G = 5;
 }
+
+// Context in which the items are requested.
+enum RequestContext {
+  reserved 1;
+  // Context not specified.
+  CONTEXT_UNSPECIFIED = 0;
+  // Requesting items on page navigation.
+  CONTEXT_PAGE_NAVIGATION = 2;
+  // Requesting items as part of a batch update.
+  CONTEXT_BATCH_UPDATE = 3;
+}

components/optimization_guide/proto/hints.proto

@@ -96,16 +96,6 @@ message Duration {
   optional int32 nanos = 2;
 }
 
-// Context in which the hints are requested.
-enum RequestContext {
-  reserved 1;
-  // Context not specified.
-  CONTEXT_UNSPECIFIED = 0;
-  // Requesting hints on page navigation.
-  CONTEXT_PAGE_NAVIGATION = 2;
-  // Requesting hints as part of a batch update.
-  CONTEXT_BATCH_UPDATE = 3;
-}
 
 enum OptimizationType {
   TYPE_UNSPECIFIED = 0;

components/optimization_guide/proto/models.proto

+// Copyright 2019 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.
+
+syntax = "proto2";
+option optimize_for = LITE_RUNTIME;
+
+package optimization_guide.proto;
+
+import "common_types.proto";
+
+// A generic handle for any type of model.
+message Model {
+  reserved 3;
+
+  oneof model {
+    DecisionTree decision_tree = 1;
+    Ensemble ensemble = 2;
+  }
+}
+
+// An ensemble prediction model consisting of an ordered sequence of models.
+// This message can be used to express bagged or boosted models.
+message Ensemble {
+  reserved 2, 3, 4;
+
+  message Member { optional Model submodel = 1; }
+  repeated Member members = 100;
+}
+
+// A decision tree model with its weight for use if included in an ensemble.
+message DecisionTree {
+  reserved 2;
+
+  repeated TreeNode nodes = 1;
+  optional float weight = 3;
+}
+
+// A node of a decision tree that is a binary deicison or a leaf.
+message TreeNode {
+  reserved 6, 7;
+
+  // Following fields are provided for convenience and better readability.
+  // Filling them in is not required.
+  optional Int32Value node_id = 1;
+  optional Int32Value depth = 2;
+  optional Int32Value subtree_size = 3;
+
+  oneof node_type {
+    BinaryNode binary_node = 4;
+    Leaf leaf = 5;
+  }
+}
+
+// A tree node that contains an inequality test that during evaluation
+// determines whether to continue the left or right child.
+message BinaryNode {
+  reserved 3, 5;
+
+  optional Int32Value left_child_id = 1;
+  optional Int32Value right_child_id = 2;
+  enum Direction {
+    LEFT = 0;
+    RIGHT = 1;
+  }
+  // When a datapoint satisfies the test, it should be propagated to the left
+  // child.
+  optional InequalityTest inequality_left_child_test = 4;
+}
+
+// Vector of values for use within Models.
+message Vector {
+  repeated Value value = 1;
+}
+
+// A leaf node of a decision tree.
+message Leaf {
+  reserved 2, 3;
+
+  optional Vector vector = 1;
+}
+
+// The ID for the features used during evaluation of a Model.
+message FeatureId {
+  reserved 2;
+
+  optional StringValue id = 1;
+}
+
+// The set of inequality operations supported by binary nodes for
+// decision tree models.
+message InequalityTest {
+  reserved 4;
+
+  // When the feature is missing, the test's outcome is undefined.
+  optional FeatureId feature_id = 1;
+  enum Type {
+    LESS_OR_EQUAL = 0;
+    LESS_THAN = 1;
+    GREATER_OR_EQUAL = 2;
+    GREATER_THAN = 3;
+  };
+  optional Type type = 2;
+  optional Value threshold = 3;
+}
+
+// Represents a single value of any type, e.g. 5 or "abc".
+message Value {
+  reserved 5;
+
+  oneof value {
+    float float_value = 1;
+    double double_value = 2;
+    int32 int32_value = 3;
+    int64 int64_value = 4;
+  }
+}
+
+// Wrapper message for `int32`.
+//
+// The JSON representation for `Int32Value` is JSON number.
+message Int32Value {
+  // The int32 value.
+  optional int32 value = 1;
+}
+
+// Wrapper message for `string`.
+//
+// The JSON representation for `StringValue` is JSON string.
+message StringValue {
+  // The string value.
+  optional string value = 1;
+}
+
+// Requests prediction models to be used for a set of optimization targets.
+message GetModelsRequest {
+  // Information about the requested models.
+  repeated ModelInfo requested_models = 1;
+  // The set of hosts to get additional metadata for, if applicable.
+  repeated string hosts = 2;
+  // Context in which this request is made.
+  //
+  // If the context matches one that requires more urgency (i.e.
+  // CONTEXT_PAGE_NAVIGATION), then no model updates will be returned for the
+  // requested models.
+  optional RequestContext request_context = 3;
+}
+
+// Response to the GetModels request.
+message GetModelsResponse {
+  // The models to be used during prediction for the requested optimization
+  // targets.
+  repeated PredictionModel models = 1;
+  // A set of model features and their values for the hosts contained in the
+  // request to be expected to be consulted with during prediction.
+  //
+  // It is not guaranteed that this set will contain an entry for every
+  // requested host.
+  repeated HostModelFeatures host_model_features = 2;
+}
+
+// Holds the prediction model for a particular optimization target.
+message PredictionModel {
+  // Information about the model.
+  optional ModelInfo model_info = 1;
+  // The model to evaluate for the attached model information.
+  //
+  // This will only be set if the model that the client claims it has is stale.
+  // It is also guaranteed that the value populated as part of this field is one
+  // that the client claims to support based on the request's client model
+  // capabilities.
+  optional Model model = 2;
+}
+
+//  Metadata for a prediction model for a specific optimization target.
+message ModelInfo {
+  // The optimization target for which the model predicts.
+  optional OptimizationTarget optimization_target = 1;
+  // The version of the model, which is specific to the optimization target.
+  optional int64 version = 2;
+  // The set of model features that are supported by the model.
+  //
+  // If in the request, this represents the set of features that the client
+  // understands how to evaluate. If in the response, this represents the set
+  // of features referenced by the model.
+  repeated ClientModelFeature supported_model_features = 3;
+  // The set of model types the requesting client can use to make predictions.
+  repeated ModelType supported_model_types = 4;
+}
+
+// The scenarios for which the optimization guide has models for.
+enum OptimizationTarget {
+  OPTIMIZATION_TARGET_UNKNOWN = 0;
+  // Should only be applied when the page load is predicted to be painful.
+  OPTIMIZATION_TARGET_PAINFUL_PAGE_LOAD = 1;
+}
+
+// The features that only the client can compute during prediction and also
+// knows how to evaluate.
+enum ClientModelFeature {
+  CLIENT_MODEL_FEATURE_UNKNOWN = 0;
+  // The effective connection type for the page load.
+  CLIENT_MODEL_FEATURE_EFFECTIVE_CONNECTION_TYPE = 1;
+  // How the current page load transitioned from the previous one.
+  CLIENT_MODEL_FEATURE_PAGE_TRANSITION = 2;
+  // The site engagement score of the main frame host for the page load.
+  CLIENT_MODEL_FEATURE_SITE_ENGAGEMENT_SCORE = 3;
+  // Whether the origin for the page load matches the origin of the previous
+  // page load.
+  CLIENT_MODEL_FEATURE_SAME_ORIGIN_NAVIGATION = 4;
+  // The mean of the duration from navigation to first contentful paint for the
+  // session.
+  CLIENT_MODEL_FEATURE_FIRST_CONTENTFUL_PAINT_SESSION_MEAN = 5;
+  // The standard deviation of the duration from navigation to first
+  // contentful paint for the session.
+  CLIENT_MODEL_FEATURE_FIRST_CONTENTFUL_PAINT_SESSION_STANDARD_DEVIATION = 6;
+  // The duration from navigation to first contentful paint for the previous
+  // page load, if applicable.
+  CLIENT_MODEL_FEATURE_FIRST_CONTENTFUL_PAINT_PREVIOUS_PAGE_LOAD = 7;
+}
+
+// The types of models that can be evaluated.
+enum ModelType {
+  MODEL_TYPE_UNKNOWN = 0;
+  // A decision tree.
+  MODEL_TYPE_DECISION_TREE = 1;
+}
+
+// A set of model features and the host that it applies to.
+message HostModelFeatures {
+  // The host that the features should be applied for.
+  optional string host = 1;
+  // The set of features and their values that apply to the host.
+  repeated ModelFeature model_features = 2;
+}
+
+// Information about a feature that is potentially referenced in a model.
+message ModelFeature {
+  // The name of the feature to match if encountered in a model.
+  optional string feature_name = 1;
+  // The value of the feature to be used during prediction.
+  oneof feature_value {
+    double double_value = 2;
+    int64 int64_value = 3;
+  }
+}