Chrome talks to Play to install WebAPKs.

chrome/browser/android/webapk/webapk_installer.cc

Index: chrome/browser/android/webapk/webapk_installer.cc
diff --git a/chrome/browser/android/webapk/webapk_installer.cc b/chrome/browser/android/webapk/webapk_installer.cc
index 348c336ccc867c6c2cc8f7b7523249ddcd72029f..be3b876affe4bb1bfc4e6e9ca4d61c8485f90d9e 100644
--- a/chrome/browser/android/webapk/webapk_installer.cc
+++ b/chrome/browser/android/webapk/webapk_installer.cc
@@ -13,6 +13,7 @@
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/memory/ref_counted.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
@@ -315,6 +316,35 @@ bool WebApkInstaller::StartUpdateUsingDownloadedWebApk(
       env, java_ref_, java_file_path);
 }
 
+bool WebApkInstaller::HasGooglePlayWebApkInstallDelegate() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  return Java_WebApkInstaller_hasGooglePlayWebApkInstallDelegate(
+      env, java_ref_);
+}
+
+bool WebApkInstaller::InstallOrUpdateWebApkFromGooglePlay(
+    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);
+
+  if (task_type_ == WebApkInstaller::INSTALL) {
+    return Java_WebApkInstaller_installWebApkFromGooglePlayAsync(
+        env, java_ref_, java_webapk_package, version, java_title, java_token);
+  } else {
+    return Java_WebApkInstaller_updateAsyncFromGooglePlay(
+        env, java_ref_, java_webapk_package, version, java_title, java_token);
+  }
+}
+
 void WebApkInstaller::OnURLFetchComplete(const net::URLFetcher* source) {
   timer_.Stop();
 
@@ -339,6 +369,17 @@ void WebApkInstaller::OnURLFetchComplete(const net::URLFetcher* source) {
     OnFailure();
     return;
   }
+
+  if (HasGooglePlayWebApkInstallDelegate()) {
+    int version = 1;

[dominickn, 2016/12/08 03:31:26]

Set this to 0 by default, and check the return value of base::StringToInt. You
should fail if the conversion didn't succeed.

[Xi Han, 2016/12/08 18:03:07]

Good catch, but maybe we still want to continue the play install in this case.
It is because the version is required by Play and they only need it when showing
a notification during installation. It would be fine if the version of the
WebAPK is just a default "1", I guess. The notification will disappear soon.

+    base::StringToInt(response->version(), &version);
+    if (!InstallOrUpdateWebApkFromGooglePlay(
+        response->package_name(), version, response->token())) {
+      OnFailure();
+    }
+    return;
+  }
+
   OnGotWebApkDownloadUrl(signed_download_url, response->package_name());
 }