[android] FlagChanger should only require root to set flags for Chrome.

build/android/pylib/flag_changer.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import constants
 import logging
 import traceback
 
 
 class FlagChanger(object):
@@ skipping 74 matching lines @@
     self._UpdateCommandLineFile()
 
   def Restore(self):
     """Restores the flags to their original state."""
     self._current_flags = self._TokenizeFlags(self._orig_line)
     self._UpdateCommandLineFile()
 
   def _UpdateCommandLineFile(self):
     """Writes out the command line to the file, or removes it if empty."""
     logging.info('Current flags: %s', self._current_flags)
-
+    # Root is not required to write to /data/local/tmp/.
+    use_root = '/data/local/tmp/' not in self._cmdline_file
     if self._current_flags:
       # The first command line argument doesn't matter as we are not actually
       # launching the chrome executable using this command line.
-      self._adb.SetProtectedFileContents(self._cmdline_file,
-                                         ' '.join(['_'] + self._current_flags))
+      cmd_line = ' '.join(['_'] + self._current_flags)
+      if use_root:
+        self._adb.SetProtectedFileContents(self._cmdline_file, cmd_line)

[frankf, 2013/10/08 23:44:52]

BTW, why do you need this every time? Can't you just open up permissions for
/data/local once?

[craigdh, 2013/10/08 23:53:30]

Let's look at cleaning up all of the *Protected/*SU apis in android commands
during the rewrite.

+        file_contents = self._adb.GetProtectedFileContents(self._cmdline_file)
+      else:
+        self._adb.SetFileContents(self._cmdline_file, cmd_line)
+        file_contents = self._adb.GetFileContents(self._cmdline_file)
+      assert len(file_contents) == 1 and file_contents[0] == cmd_line, (
+          'Failed to set the command line file at %s' % self._cmdline_file)
     else:
-      self._adb.RunShellCommand('su -c rm ' + self._cmdline_file)
+      if use_root:
+        self._adb.RunShellCommandWithSU('rm ' + self._cmdline_file)
+      else:
+        self._adb.RunShellCommand('rm ' + self._cmdline_file)
+      assert not self._adb.FileExistsOnDevice(self._cmdline_file), (
+          'Failed to remove the command line file at %s' % self._cmdline_file)
 
   def _TokenizeFlags(self, line):
     """Changes the string containing the command line into a list of flags.
 
     Follows similar logic to CommandLine.java::tokenizeQuotedArguments:
     * Flags are split using whitespace, unless the whitespace is within a
       pair of quotation marks.
     * Unlike the Java version, we keep the quotation marks around switch
       values since we need them to re-create the file when new flags are
       appended.
@@ skipping 28 matching lines @@
 
     # Tack on the last flag.
     if not current_flag:
       if within_quotations:
         logging.warn('Unterminated quoted argument: ' + line)
     else:
       tokenized_flags.append(current_flag)
 
     # Return everything but the program name.
     return tokenized_flags[1:]