[Android] Enable lint warnings by default.

build/common.gypi

 # 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1009 matching lines @@
     # Set to 1 to enable java code coverage. Instruments classes during build
     # to produce .ec files during runtime.
     'emma_coverage%': 0,
 
     # EMMA filter string consisting of a list of inclusion/exclusion patterns
     # separated with whitespace and/or comma. Only has effect if
     # 'emma_coverage=1'.
     'emma_filter%': '',
 
     # Set to 1 to enable running Android lint on java/class files.
-    'android_lint%': 0,
+    'android_lint%': 1,
 
     # Set to 1 to force Visual C++ to use legacy debug information format /Z7.
     # This is useful for parallel compilation tools which can't support /Zi.
     # Only used on Windows.
     'win_z7%' : 0,
 
     # Although base/allocator lets you select a heap library via an
     # environment variable, the libcmt shim it uses sometimes gets in
     # the way.  To disable it entirely, and switch to normal msvcrt, do e.g.
     #  'win_use_allocator_shim': 0,
@@ skipping 3755 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }