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..91706d0d2260116930a317f861ec9245006deeb8 100644
--- a/chrome/browser/android/webapk/webapk_installer.h
+++ b/chrome/browser/android/webapk/webapk_installer.h
@@ -38,6 +38,12 @@ class WebApkIconHasher;
 // Java WebApkInstaller counterpart.
 class WebApkInstaller : public net::URLFetcherDelegate {
  public:
+  enum TaskType {

[dominickn, 2016/09/27 03:16:24]

Nit: is this enum going to be used outside of the class?

[Xi Han, 2016/09/27 12:55:13]

This enum is used by CreateSubDirAndSetPermissionsInBackground() in the
anonymous namespace. The function is called by PostTaskAndReplyWithResult() as
the first function. Since we need a return value from
CreateSubDirAndSetPermissionsInBackground(), so it doesn't allow to be bound
with a weak pointer. I have to declare it as a function in anonymous namespace.
Are you ok with it? Or do you prefer to post task back without using
PostTaskAndReplyWithResult()?

[dominickn, 2016/09/28 00:56:28]

It looks like task_type is only used in
CreateSubDirAndSetPermissionsInBackground to choose which suffix to add to the
directory. Instead, you could make that method take a base::StringPiece argument
which is the suffix, and just append it. Then the caller inside WebApkInstaller
uses task_type_ to work out what suffix is necessary, saving you from exposing
the internal TaskType detail. Would that work?

[Xi Han, 2016/09/28 01:54:24]

Done.

+    UNDEFINED,
+    INSTALL,
+    UPDATE,
+  };
+
   // Called when the creation/updating of a WebAPK is finished or failed.
   // Parameters:
   // - whether the process succeeds.
@@ -109,12 +115,6 @@ class WebApkInstaller : public net::URLFetcherDelegate {
   void OnSuccess();
 
  private:
-  enum TaskType {
-    UNDEFINED,
-    INSTALL,
-    UPDATE,
-  };
-
   // Create the Java object.
   void CreateJavaRef();
 
@@ -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.