Don't trigger HW acceleration from Toasts on low-end devices.

PRESUBMIT.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.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into depot_tools.
 """
 
@@ skipping 1294 matching lines @@
     import checkstyle
   finally:
     # Restore sys.path to what it was before.
     sys.path = original_sys_path
 
   return checkstyle.RunCheckstyle(
       input_api, output_api, 'tools/android/checkstyle/chromium-style-5.0.xml',
       black_list=_EXCLUDED_PATHS + input_api.DEFAULT_BLACK_LIST)
 
 
+def _CheckAndroidToastUsage(input_api, output_api):
+  """Checks that code uses org.chromium.ui.widget.Toast instead of
+     android.widget.Toast (Chromium Toast doesn't force hardware
+     acceleration on low-end devices, saving memory).
+  """
+  toast_import_pattern = input_api.re.compile(
+      r'^import android\.widget\.Toast;$')
+
+  errors = []
+
+  sources = lambda affected_file: input_api.FilterSourceFile(
+      affected_file,
+      black_list=(_EXCLUDED_PATHS +
+                  _TEST_CODE_EXCLUDED_PATHS +
+                  input_api.DEFAULT_BLACK_LIST +
+                  (r'^chromecast[\\\/].*',
+                   r'^remoting[\\\/].*')),
+      white_list=(r'.*\.java$',))
+
+  for f in input_api.AffectedSourceFiles(sources):
+    for line_num, line in f.ChangedContents():
+      if toast_import_pattern.search(line):
+        errors.append("%s:%d" % (f.LocalPath(), line_num))
+
+  results = []
+
+  if errors:
+    results.append(output_api.PresubmitError(
+        'android.widget.Toast usage is detected. Android toasts use hardware'
+        ' acceleration, and can be\ncostly on low-end devices. Please use'
+        ' org.chromium.ui.widget.Toast instead.\n'
+        'Contact dskiba@chromium.org if you have any questions.',
+        errors))
+
+  return results
+
+
 def _CheckAndroidCrLogUsage(input_api, output_api):
   """Checks that new logs using org.chromium.base.Log:
     - Are using 'TAG' as variable name for the tags (warn)
     - Are using the suggested name format for the tags: "cr.<PackageTag>" (warn)
     - Are using a tag that is shorter than 23 characters (error)
   """
   cr_log_import_pattern = input_api.re.compile(
       r'^import org\.chromium\.base\.Log;$', input_api.re.MULTILINE)
   class_in_base_pattern = input_api.re.compile(
       r'^package org\.chromium\.base;$', input_api.re.MULTILINE)
@@ skipping 198 matching lines @@
           results.append(output_api.PresubmitError(
               "%s:%d: Use of deprecated JS %s, use %s instead" %
               (fpath.LocalPath(), lnum, deprecated, replacement)))
   return results
 
 
 def _AndroidSpecificOnUploadChecks(input_api, output_api):
   """Groups checks that target android code."""
   results = []
   results.extend(_CheckAndroidCrLogUsage(input_api, output_api))
+  results.extend(_CheckAndroidToastUsage(input_api, output_api))
   return results
 
 
 def _CommonChecks(input_api, output_api):
   """Checks common to both upload and commit."""
   results = []
   results.extend(input_api.canned_checks.PanProjectChecks(
       input_api, output_api,
       excluded_paths=_EXCLUDED_PATHS + _TESTRUNNER_PATHS))
   results.extend(_CheckAuthorizedAuthor(input_api, output_api))
@@ skipping 339 matching lines @@
   for master in masters:
     try_config.setdefault(master, {})
     for builder in masters[master]:
       # Do not trigger presubmit builders, since they're likely to fail
       # (e.g. OWNERS checks before finished code review), and we're
       # running local presubmit anyway.
       if 'presubmit' not in builder:
         try_config[master][builder] = ['defaulttests']
 
   return try_config