[mini_installer] Remove code to delete files left behind by previous runs.

Once upon a time, mini_installer.exe created a directory in %TMP% in
which to place files while it performed its work. Since it may fail to
delete these files (e.g., due to crashes or interference by A/V
software), it was given the power to delete files left behind by
previous executions. This is all well and good, except that organic
system-level installs did this work in a user's %TMP% directory rather
than in the system's. Starting in r798844, mini_installer now puts its
work directory next to itself. For installs driven by Google Update, GU
will take care of (eventually) deleting anything left behind. Since this
appears to be working reliably, we no longer need the %TMP% cleanup
code.

One caveat to this change is that files/dirs may once again accumulate
in %TMP% if mini_installer is run from a directory in which it does not
have write access. This will never be the case for proper Google Chrome
installs.

BUG=1125018
R=forshaw@chromium.org

Change-Id: I50a768585d25ebdd508fc88f8036580a01bd8727
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2484651Reviewed-by: James Forshaw <forshaw@chromium.org>
Commit-Queue: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819537}

chrome/installer/mini_installer/mini_installer.cc

@@ -736,115 +736,6 @@ bool GetWorkDir(HMODULE module,
          CreateWorkDir(base_path.get(), work_dir, exit_code);
 }
 
-// Returns true for ".." and "." directories.
-bool IsCurrentOrParentDirectory(const wchar_t* dir) {
-  return dir && dir[0] == L'.' &&
-         (dir[1] == L'\0' || (dir[1] == L'.' && dir[2] == L'\0'));
-}
-
-// Best effort directory tree deletion including the directory specified
-// by |path|, which must not end in a separator.
-// The |path| argument is writable so that each recursion can use the same
-// buffer as was originally allocated for the path.  The path will be unchanged
-// upon return.
-void RecursivelyDeleteDirectory(PathString* path) {
-  // |path| will never have a trailing backslash.
-  size_t end = path->length();
-  if (!path->append(L"\\*.*"))
-    return;
-
-  WIN32_FIND_DATA find_data = {0};
-  HANDLE find = ::FindFirstFile(path->get(), &find_data);
-  if (find != INVALID_HANDLE_VALUE) {
-    do {
-      // Chrome never creates files/directories with reparse points (i.e.,
-      // mounted folders, links, etc), so never try to delete them.
-      if (find_data.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)
-        continue;
-
-      // Use the short name if available to make the most of our buffer.
-      const wchar_t* name = find_data.cAlternateFileName[0]
-                                ? find_data.cAlternateFileName
-                                : find_data.cFileName;
-      if (IsCurrentOrParentDirectory(name))
-        continue;
-
-      path->truncate_at(end + 1);  // Keep the trailing backslash.
-      if (!path->append(name))
-        continue;  // Continue in spite of too long names.
-
-      if (find_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
-        RecursivelyDeleteDirectory(path);
-      else
-        ::DeleteFile(path->get());
-    } while (::FindNextFile(find, &find_data));
-    ::FindClose(find);
-  }
-
-  // Restore the path and delete the directory before we return.
-  path->truncate_at(end);
-  ::RemoveDirectory(path->get());
-}
-
-// Enumerates subdirectories of |parent_dir| and deletes all subdirectories
-// that match with a given |prefix|.  |parent_dir| must have a trailing
-// backslash.
-// The process is done on a best effort basis, so conceivably there might
-// still be matches left when the function returns.
-void DeleteDirectoriesWithPrefix(const wchar_t* parent_dir,
-                                 const wchar_t* prefix) {
-  // |parent_dir| is guaranteed to always have a trailing backslash.
-  PathString spec;
-  if (!spec.assign(parent_dir) || !spec.append(prefix) || !spec.append(L"*.*"))
-    return;
-
-  WIN32_FIND_DATA find_data = {0};
-  HANDLE find = ::FindFirstFileEx(spec.get(), FindExInfoStandard, &find_data,
-                                  FindExSearchLimitToDirectories, nullptr, 0);
-  if (find == INVALID_HANDLE_VALUE)
-    return;
-
-  PathString path;
-  do {
-    // Chrome never creates files/directories with reparse points (i.e., mounted
-    // folders, links, etc), so never try to delete them.
-    if (find_data.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)
-      continue;
-
-    if (find_data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
-      // Use the short name if available to make the most of our buffer.
-      const wchar_t* name = find_data.cAlternateFileName[0]
-                                ? find_data.cAlternateFileName
-                                : find_data.cFileName;
-      if (IsCurrentOrParentDirectory(name))
-        continue;
-      if (path.assign(parent_dir) && path.append(name))
-        RecursivelyDeleteDirectory(&path);
-    }
-  } while (::FindNextFile(find, &find_data));
-  ::FindClose(find);
-}
-
-// Attempts to free up space by deleting temp directories that previous
-// installer runs have failed to clean up.
-void DeleteOldChromeTempDirectories() {
-  static const wchar_t* const kDirectoryPrefixes[] = {
-      kTempPrefix,
-      L"chrome_"  // Previous installers created directories with this prefix
-                  // and there are still some lying around.
-  };
-
-  ProcessExitResult ignore(SUCCESS_EXIT_CODE);
-  PathString temp;
-  // GetTempDir always returns a path with a trailing backslash.
-  if (!GetTempDir(&temp, &ignore))
-    return;
-
-  for (size_t i = 0; i < _countof(kDirectoryPrefixes); ++i) {
-    DeleteDirectoriesWithPrefix(temp.get(), kDirectoryPrefixes[i]);
-  }
-}
-
 // Checks the command line for specific mini installer flags.
 // If the function returns true, the command line has been processed and all
 // required actions taken.  The installer must exit and return the returned
@@ -864,12 +755,6 @@ bool ProcessNonInstallOperations(const Configuration& configuration,
 }
 
 ProcessExitResult WMain(HMODULE module) {
-  // Always start with deleting potential leftovers from previous installations.
-  // This can make the difference between success and failure.  We've seen
-  // many installations out in the field fail due to out of disk space problems
-  // so this could buy us some space.
-  DeleteOldChromeTempDirectories();
-
   ProcessExitResult exit_code = ProcessExitResult(SUCCESS_EXIT_CODE);
 
   // Parse configuration from the command line and resources.