Download WebAPK into a WebAPK-specifc directory, and delete all cached ones.

chrome/browser/android/webapk/webapk_installer.h

Index: chrome/browser/android/webapk/webapk_installer.h
diff --git a/chrome/browser/android/webapk/webapk_installer.h b/chrome/browser/android/webapk/webapk_installer.h
index eb24f5b2ce428e14f5fb30f19b64f6a1de3fc09b..d30a83ace5195794e5b5cb9d0a1809b790774c48 100644
--- a/chrome/browser/android/webapk/webapk_installer.h
+++ b/chrome/browser/android/webapk/webapk_installer.h
@@ -149,6 +149,11 @@ class WebApkInstaller : public net::URLFetcherDelegate {
   void OnGotWebApkDownloadUrl(const GURL& download_url,
                               const std::string& package_name);
 
+  // Called once the sub directory to store the downloaded WebAPK was
+  // created with permissions set properly or if creation failed.
+  void OnCreatedSubDirAndSetPermissions(const GURL& download_url,
+                                        const base::FilePath& file_path);
+
   // Called once the WebAPK has been downloaded. Makes the downloaded WebAPK
   // world readable and installs the WebAPK if the download was successful.
   // |file_path| is the file path that the WebAPK was downloaded to.