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..d5fd00c76c7e4aebdd2c7f55c01fbbdeb4fbf0c1 100644
--- a/chrome/browser/download/download_target_determiner.h
+++ b/chrome/browser/download/download_target_determiner.h
@@ -23,6 +23,9 @@ class DownloadPrefs;
 
 namespace content {
 enum DownloadDangerType;
+#if defined(OS_ANDROID)
+class DownloadControllerAndroid;
+#endif
 }
 
 // Determines the target of the download.
@@ -86,6 +89,12 @@ class DownloadTargetDeterminer
   static bool IsAdobeReaderUpToDate();
 #endif
 
+#if defined(OS_ANDROID)
+  // Allows unit test to mock DownloadControllerAndroid.
+  static void SetDownloadControllerAndroidForTestings(
+      content::DownloadControllerAndroid* download_controller);
+#endif
+
  private:
   // The main workflow is controlled via a set of state transitions. Each state
   // has an associated handler. The handler for STATE_FOO is DoFoo. Each handler
@@ -93,6 +102,7 @@ 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 +158,15 @@ class DownloadTargetDeterminer
 
   // === Main workflow ===
 
+  // Prompts user for file access if necessary.
+  // Next state:
+  // - STATE_GENERATE_TARGET_PATH.
+  Result DoPromptUserForPermission();
+
+  // Callback invoked after the file access prompt completes. Cancels the
+  // download if the user doesn't grant file access.
+  void PromptUserForPermissionDone(bool granted);
+
   // Generates an initial target path. This target is based only on the state of
   // the download item.
   // Next state: