Revert of Migrate DeviceUtils.ReadFile to adb_wrapper

build/android/pylib/device/device_utils.py

Index: build/android/pylib/device/device_utils.py
diff --git a/build/android/pylib/device/device_utils.py b/build/android/pylib/device/device_utils.py
index f416c7866ae44194b404689a5b3eb303f05b2e70..0ff3a8454799eccc160b4aaf357b1f1bb34dc2d3 100644
--- a/build/android/pylib/device/device_utils.py
+++ b/build/android/pylib/device/device_utils.py
@@ -54,13 +54,6 @@
     CommandFailedError if we fail to kill or restart the server.
   """
   pylib.android_commands.AndroidCommands().RestartAdbServer()
-
-
-def _JoinLines(lines):
-  # makes sure that the last line is also terminated, and is more memory
-  # efficient than first appending an end-line to each line and then joining
-  # all of them together.
-  return ''.join(s for line in lines for s in (line, '\n'))
 
 
 class DeviceUtils(object):
@@ -864,8 +857,7 @@
           str(e), str(self)), None, sys.exc_info()[2]
 
   @decorators.WithTimeoutAndRetriesFromInstance()
-  def ReadFile(self, device_path, as_root=False,
-               timeout=None, retries=None):
+  def ReadFile(self, device_path, as_root=False, timeout=None, retries=None):
     """Reads the contents of a file from the device.
 
     Args:
@@ -877,17 +869,22 @@
       retries: number of retries
 
     Returns:
-      The contents of |device_path| as a string. Contents are intepreted using
-      universal newlines, so the caller will see them encoded as '\n'. Also,
-      all lines will be terminated.
-
-    Raises:
-      AdbCommandFailedError if the file can't be read.
-      CommandTimeoutError on timeout.
-      DeviceUnreachableError on missing device.
-    """
-    return _JoinLines(self.RunShellCommand(
-        ['cat', device_path], as_root=as_root, check_return=True))
+      The contents of the file at |device_path| as a list of lines.
+
+    Raises:
+      CommandFailedError if the file can't be read.
+      CommandTimeoutError on timeout.
+      DeviceUnreachableError on missing device.
+    """
+    # TODO(jbudorick) Evaluate whether we want to return a list of lines after
+    # the implementation switch, and if file not found should raise exception.
+    if as_root:
+      if not self.old_interface.CanAccessProtectedFileContents():
+        raise device_errors.CommandFailedError(
+          'Cannot read from %s with root privileges.' % device_path)
+      return self.old_interface.GetProtectedFileContents(device_path)
+    else:
+      return self.old_interface.GetFileContents(device_path)
 
   @decorators.WithTimeoutAndRetriesFromInstance()
   def WriteFile(self, device_path, contents, as_root=False, force_push=False,