Migrate device utils WriteFile to AdbWrapper

tools/telemetry/telemetry/core/backends/chrome/android_browser_backend.py

Index: tools/telemetry/telemetry/core/backends/chrome/android_browser_backend.py
diff --git a/tools/telemetry/telemetry/core/backends/chrome/android_browser_backend.py b/tools/telemetry/telemetry/core/backends/chrome/android_browser_backend.py
index 3e416736f2a52abb4d358ad960f4ece0af43a0a2..130362b29347a61a8e54f3d7af1a83890cfce1e8 100644
--- a/tools/telemetry/telemetry/core/backends/chrome/android_browser_backend.py
+++ b/tools/telemetry/telemetry/core/backends/chrome/android_browser_backend.py
@@ -216,7 +216,6 @@ class AndroidBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
     content = ' '.join(QuoteIfNeeded(arg) for arg in args)
     cmdline_file = self._backend_settings.GetCommandLineFile(
         self._adb.IsUserBuild())
-    as_root = self._adb.device().old_interface.CanAccessProtectedFileContents()
 
     try:
       # Save the current command line to restore later, except if it appears to
@@ -226,7 +225,7 @@ class AndroidBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
       self._saved_cmdline = ''.join(self._adb.device().ReadFile(cmdline_file))
       if '--host-resolver-rules' in self._saved_cmdline:
         self._saved_cmdline = ''
-      self._adb.device().WriteTextFile(cmdline_file, content, as_root=as_root)
+      self._adb.device().WriteFile(cmdline_file, content, as_root=True)

[perezju, 2014/11/11 23:05:35]

With the new semantics of as_root=True (use 'su' only if needed and available),
this will "do the right thing" also when running on a user build. No more need
to figure out the "correct" value to pass.

     except device_errors.CommandFailedError:
       logging.critical('Cannot set Chrome command line. '
                        'Fix this by flashing to a userdebug build.')
@@ -235,9 +234,8 @@ class AndroidBrowserBackend(chrome_browser_backend.ChromeBrowserBackend):
   def _RestoreCommandLine(self):
     cmdline_file = self._backend_settings.GetCommandLineFile(
         self._adb.IsUserBuild())
-    as_root = self._adb.device().old_interface.CanAccessProtectedFileContents()
-    self._adb.device().WriteTextFile(cmdline_file, self._saved_cmdline,
-                                     as_root=as_root)
+    self._adb.device().WriteFile(cmdline_file, self._saved_cmdline,
+                                 as_root=True)
 
   def Start(self):
     self._SetUpCommandLine()