Add DownloadClient for optimization guide prediction models

Will add the client itself in a separate CL
This is basically following the template of https://chromium-review.googlesource.com/c/chromium/src/+/1416131

Bug: 1146151
Change-Id: I77a32bdf4021768d902f9975c1077f3c0fbd3c77
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2522399Reviewed-by: Min Qin <qinmin@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Michael Crouse <mcrouse@chromium.org>
Commit-Queue: Sophie Chang <sophiechang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825904}

components/download/internal/background_service/logger_impl.cc

@@ -56,6 +56,8 @@ std::string ClientToString(DownloadClient client) {
       return "MountainInternal";
     case DownloadClient::PLUGIN_VM_IMAGE:
       return "PluginVmImage";
+    case DownloadClient::OPTIMIZATION_GUIDE_PREDICTION_MODELS:
+      return "OptimizationGuidePredictionModels";
     case DownloadClient::BOUNDARY:  // Intentional fallthrough.
     default:
       NOTREACHED();

components/download/internal/background_service/proto/entry.proto

@@ -23,7 +23,10 @@ enum DownloadClient {
   DEBUGGING = 6;
   MOUNTAIN_INTERNAL = 7;
   PLUGIN_VM_IMAGE = 8;
-  BOUNDARY = 9;
+  OPTIMIZATION_GUIDE_PREDICTION_MODELS = 9;
+
+  // New clients should be added above here.
+  BOUNDARY = 10;
 }
 
 // Stores the request params, internal state, metrics and metadata associated

components/download/internal/background_service/proto_conversions.cc

@@ -72,6 +72,8 @@ protodb::DownloadClient ProtoConversions::DownloadClientToProto(
       return protodb::DownloadClient::MOUNTAIN_INTERNAL;
     case DownloadClient::PLUGIN_VM_IMAGE:
       return protodb::DownloadClient::PLUGIN_VM_IMAGE;
+    case DownloadClient::OPTIMIZATION_GUIDE_PREDICTION_MODELS:
+      return protodb::DownloadClient::OPTIMIZATION_GUIDE_PREDICTION_MODELS;
     case DownloadClient::BOUNDARY:
       return protodb::DownloadClient::BOUNDARY;
   }
@@ -101,6 +103,8 @@ DownloadClient ProtoConversions::DownloadClientFromProto(
       return DownloadClient::MOUNTAIN_INTERNAL;
     case protodb::DownloadClient::PLUGIN_VM_IMAGE:
       return DownloadClient::PLUGIN_VM_IMAGE;
+    case protodb::DownloadClient::OPTIMIZATION_GUIDE_PREDICTION_MODELS:
+      return DownloadClient::OPTIMIZATION_GUIDE_PREDICTION_MODELS;
     case protodb::DownloadClient::BOUNDARY:
       return DownloadClient::BOUNDARY;
   }

components/download/internal/background_service/stats.cc

@@ -96,6 +96,8 @@ std::string ClientToHistogramSuffix(DownloadClient client) {
       return "MountainInternal";
     case DownloadClient::PLUGIN_VM_IMAGE:
       return "PluginVmImage";
+    case DownloadClient::OPTIMIZATION_GUIDE_PREDICTION_MODELS:
+      return "OptimizationGuidePredictionModels";
     case DownloadClient::BOUNDARY:
       NOTREACHED();
       break;

components/download/public/background_service/clients.h

@@ -41,7 +41,10 @@ enum class DownloadClient {
 
   PLUGIN_VM_IMAGE = 5,
 
-  BOUNDARY = 6,
+  OPTIMIZATION_GUIDE_PREDICTION_MODELS = 6,
+
+  // New clients should be added above here.
+  BOUNDARY = 7,
 };
 
 using DownloadClientMap = std::map<DownloadClient, std::unique_ptr<Client>>;

tools/metrics/histograms/histograms_xml/histogram_suffixes_list.xml

@@ -5457,6 +5457,8 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   <suffix name="Debugging" label="Debugging client."/>
   <suffix name="MountainInternal" label="Mountain internal client."/>
   <suffix name="OfflinePage" label="Offline page prefetch."/>
+  <suffix name="OptimizationGuidePredictionModels"
+      label="Optimization Guide prediction models."/>
   <suffix name="PluginVmImage" label="PluginVm image."/>
   <affected-histogram name="Download.Service.Clients.InflatedFullBrowser"/>
   <affected-histogram name="Download.Service.Request.ClientAction"/>