Add calls to the server to request WebAPK updates.

chrome/browser/android/webapk/webapk.proto

Index: chrome/browser/android/webapk/webapk.proto
diff --git a/chrome/browser/android/webapk/webapk.proto b/chrome/browser/android/webapk/webapk.proto
index 8bebf1d0291cdc251bf8674ee59d6a69bd97a2f8..ace48968770cb6eda53e4acffd9d2020e1f7b025 100644
--- a/chrome/browser/android/webapk/webapk.proto
+++ b/chrome/browser/android/webapk/webapk.proto
@@ -14,29 +14,46 @@ message CreateWebApkRequest {
   optional WebApk webapk = 1;
 }
 
-// Response to CreateWebApkRequest.
-message CreateWebApkResponse {
+// Creates a updated WebAPK on the server and returns URL to download WebAPK
+// from Google Play.
+message UpdateWebApkRequest {
+  optional WebApk webapk = 1;
+}
+
+// Response after creating or updating a WebAPK.
+message WebApkResponse {
   // Package name to install WebAPK at.
   optional string webapk_package_name = 1;
 
-  // URL to download WebAPK.
-  optional string signed_download_url = 2;
+  // Version code of the WebAPK.
+  optional string version = 2;
+
+  // URL to download WebAPK from Google Play.
+  optional string signed_download_url = 3;
+
+  reserved 4;
 }
 
 message WebApk {
+  // Package name of the WebAPK.
+  optional string package_name = 1;
+
+  // Version code of the WebAPK.
+  optional string version = 2;
+
   // The URL of the Web App Manifest.
-  optional string manifest_url = 2;
+  optional string manifest_url = 3;
 
   // Chrome's package name.
-  optional string requester_application_package = 4;
+  optional string requester_application_package = 5;
 
   // Chrome's version.
-  optional string requester_application_version = 5;
+  optional string requester_application_version = 6;
 
   // The Web App Manifest.
-  optional WebAppManifest manifest = 6;
+  optional WebAppManifest manifest = 7;
 
-  reserved 1, 3;
+  reserved 4;
 }
 
 // Contains data from the Web App Manifest.