Fix adb_chrome_public_command_line for Android M & refactor into a helper .sh

build/android/adb_command_line_functions.sh

+#!/bin/bash
+#
+# Copyright 2015 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.
+
+# Variables must be set before calling:
+# CMD_LINE_FILE - Path on device to flags file.
+# REQUIRES_SU - Set to 1 if path requires root.
+function set_command_line() {
+  SU_CMD=""
+  if [[ "$REQUIRES_SU" = 1 ]]; then

[jbudorick, 2015/06/01 15:43:24]

-eq

?

[agrieve, 2015/06/01 15:58:19]

Since REQUIRES_SU can be unset, I think = is more appropriate.

+    # Older androids accept "su -c", while newer use "su uid".
+    IS_OLD_STYLE=$(adb shell su -c echo 1 2>/dev/null)

[jbudorick, 2015/06/01 15:43:24]

I'm not crazy about this.

[agrieve, 2015/06/01 15:58:19]

suggestion for what you would be crazy for?

[jbudorick, 2015/06/01 17:44:21]

I would break on SDK level (ro.build.version.sdk) -- maybe do su 0 for L+ and su
-c otherwise. (That's what we'll probably wind up doing on the python side in
https://code.google.com/p/chromium/codesearch#chromium/src/build/android/pyli...)

+    SU_CMD="su -c"
+    if [[ -n $IS_OLD_STYLE ]]; then
+      SU_CMD="su 0"

[jbudorick, 2015/06/01 15:43:24]

Does this style work in older android versions?

[agrieve, 2015/06/01 15:58:19]

From my quick test, seems to work back got JB, but not on ICS.

+    fi
+  fi
+
+  if [ $# -eq 0 ] ; then
+    # If nothing specified, print the command line (stripping off "chrome ")
+    adb shell "cat $CMD_LINE_FILE 2>/dev/null | cut -d ' ' -s -f2-"
+  elif [ $# -eq 1 ] && [ "$1" = '' ] ; then
+    # If given an empty string, delete the command line.
+    set -x
+    adb shell $SU_CMD rm $CMD_LINE_FILE >/dev/null
+  else
+    # Else set it.
+    set -x
+    adb shell "echo 'chrome $*' | $SU_CMD dd of=$CMD_LINE_FILE"
+    # Prevent other apps from modifying flags (this can create security issues).
+    adb shell $SU_CMD chmod 0664 $CMD_LINE_FILE
+  fi
+}
+