Prompt user for file access permission before download starts

chrome/browser/download/download_target_determiner.h

Index: chrome/browser/download/download_target_determiner.h
diff --git a/chrome/browser/download/download_target_determiner.h b/chrome/browser/download/download_target_determiner.h
index 0bb4cb034e297f6e0540ce9aee9d75502a64efe0..46f17a778141fef5b825339ec48db7da1e1c61e5 100644
--- a/chrome/browser/download/download_target_determiner.h
+++ b/chrome/browser/download/download_target_determiner.h
@@ -93,6 +93,7 @@ class DownloadTargetDeterminer
   // Result indicating how the workflow should proceed. The loop ends when a
   // handler returns COMPLETE.
   enum State {
+    STATE_PROMPT_USER_FOR_PERMISSION,
     STATE_GENERATE_TARGET_PATH,
     STATE_NOTIFY_EXTENSIONS,
     STATE_RESERVE_VIRTUAL_PATH,
@@ -148,6 +149,17 @@ class DownloadTargetDeterminer
 
   // === Main workflow ===
 
+  // Prompts user for file access if necessary.
+  // Next state:
+  // - STATE_GENERATE_TARGET_PATH.
+  Result DoPromptUserForPermission();
+
+#if defined(OS_ANDROID)
+  // Callback invoked after the file access prompt completes. Cancels the
+  // download if the user doesn't grant file access.
+  void PromptUserForPermissionDone(bool granted);
+#endif
+
   // Generates an initial target path. This target is based only on the state of
   // the download item.
   // Next state: