[Android] Send minidump service intent as root.

Also improve exception message.

BUG=None
NOTRY=True

Review URL: https://codereview.chromium.org/76973003

git-svn-id: http://src.chromium.org/svn/trunk/src/build@236280 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

android/pylib/android_commands.py

@@ -750,8 +750,9 @@ class AndroidCommands(object):
       (constants.PACKAGE_INFO['chrome'].package,
        package,
        constants.PACKAGE_INFO['chrome'].package))
-    am_output = self.RunShellCommand(cmd)
-    assert am_output and 'Starting' in am_output[-1], 'Service failed to start'
+    am_output = self.RunShellCommandWithSU(cmd)
+    assert am_output and 'Starting' in am_output[-1], (
+        'Service failed to start: %s' % am_output)
     time.sleep(15)
 
   def BroadcastIntent(self, package, intent, *args):