Chrome talks to Play to install WebAPKs.

chrome/browser/android/webapk/webapk_installer.cc

 // Copyright 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.
 
 #include "chrome/browser/android/webapk/webapk_installer.h"
 
+#include <stdlib.h>
+
 #include "base/android/build_info.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/android/path_utils.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/task_runner_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/android/chrome_feature_list.h"
 #include "chrome/browser/android/shortcut_helper.h"
 #include "chrome/browser/android/webapk/webapk.pb.h"
 #include "chrome/browser/android/webapk/webapk_icon_hasher.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/common/chrome_switches.h"
 #include "components/variations/variations_associated_data.h"
 #include "components/version_info/version_info.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/manifest_util.h"
 #include "jni/WebApkInstaller_jni.h"
 #include "net/http/http_status_code.h"
 #include "net/url_request/url_fetcher.h"
 #include "ui/gfx/codec/png_codec.h"
 #include "url/gurl.h"
 
@@ skipping 286 matching lines @@
   if (!response->ParseFromString(response_string)) {
     OnFailure();
     return;
   }
 
   GURL signed_download_url(response->signed_download_url());
   if (!signed_download_url.is_valid() || response->package_name().empty()) {
     OnFailure();
     return;
   }
+
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnablePlayInstallWebApk)) {
+    InstallWebApkFromPlayStore(response->package_name(),
+                               std::atoi(response->version().c_str()),

[pkotwicz, 2016/11/23 03:11:28]

Random thought: Why isn't the version part of the token?

[Xi Han, 2016/11/23 15:43:46]

Scott confirmed that the token is just a random number and doesn't contain any
other information, all the useful information is cached on the server.
Personally, I would prefer to keep the version as a separate field like now.

[pkotwicz, 2016/11/23 15:56:38]

I dislike that the token is a random number. If it's truly random, than there is
a small chance of collisions and it is possible for a person to install a
different WebAPK than they intended. Can it be the WebAPK id with a random
number appended to it?

I still don't understand why passing the version to Google Play is important. Is
passing the version number a "Google Play requirement" or a "WebAPK server
requirement"?

[Xi Han, 2016/11/23 16:44:42]

As discussed offline, the version is required by Play, and we keep it as it is
now.

+                               response->token());
+    return;
+  }
+
   OnGotWebApkDownloadUrl(signed_download_url, response->package_name());
 }
 
 void WebApkInstaller::DownloadAppIconAndComputeMurmur2Hash() {
   // Safeguard. WebApkIconHasher crashes if asked to fetch an invalid URL.
   if (!shortcut_info_.icon_url.is_valid()) {
     OnFailure();
     return;
   }
 
@@ skipping 51 matching lines @@
 
   url_fetcher_ =
       net::URLFetcher::Create(server_url, net::URLFetcher::POST, this);
   url_fetcher_->SetRequestContext(request_context_getter_);
   std::string serialized_request;
   request_proto->SerializeToString(&serialized_request);
   url_fetcher_->SetUploadData(kProtoMimeType, serialized_request);
   url_fetcher_->Start();
 }
 
+void WebApkInstaller::InstallWebApkFromPlayStore(
+    const std::string& package_name, int version, const std::string& token) {
+  webapk_package_ = package_name;
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  base::android::ScopedJavaLocalRef<jstring> java_webapk_package =
+      base::android::ConvertUTF8ToJavaString(env, webapk_package_);
+  base::android::ScopedJavaLocalRef<jstring> java_title =
+      base::android::ConvertUTF16ToJavaString(env, shortcut_info_.user_title);
+  base::android::ScopedJavaLocalRef<jstring> java_token =
+      base::android::ConvertUTF8ToJavaString(env, token);
+
+  Java_WebApkInstaller_installWebApkFromPlayStoreAsyncAndMonitorInstallation(
+      env, java_ref_, java_webapk_package, version, java_title, java_token);
+}
+
 void WebApkInstaller::OnGotWebApkDownloadUrl(const GURL& download_url,
                                              const std::string& package_name) {
   webapk_package_ = package_name;
 
   base::PostTaskAndReplyWithResult(
       GetBackgroundTaskRunner().get(), FROM_HERE,
       base::Bind(&CreateSubDirAndSetPermissionsInBackground,
                  task_type_ == WebApkInstaller::INSTALL ? "install" : "update",
                  package_name),
       base::Bind(&WebApkInstaller::OnCreatedSubDirAndSetPermissions,
@@ skipping 92 matching lines @@
 
 void WebApkInstaller::OnSuccess() {
   finish_callback_.Run(true, webapk_package_);
   delete this;
 }
 
 void WebApkInstaller::OnFailure() {
   finish_callback_.Run(false, webapk_package_);
   delete this;
 }