Android: Silence ProGuard output about duplicate input files

We already were silencing most of this via stdout filtering, but there
are still some third-party libraries that were showing warnings. E.g.:

Warning: can't write resource [META-INF/maven/com.google.guava/guava/pom.xml] (Duplicate zip entry [espresso-core-release-no-dep.jar:META-INF/maven/com.google.guava/guava/pom.xml])

This change tells ProGuard to ignore these files, rather than filtering
the resulting errors

Change-Id: I288507de1f2c5576fbb0fea8bfebb189b2603c92
Reviewed-on: https://chromium-review.googlesource.com/963699Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Commit-Queue: agrieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543527}

build/android/gyp/util/proguard_util.py

@@ -16,7 +16,7 @@ class _ProguardOutputFilter(object):
 
   IGNORE_RE = re.compile(
       r'Pro.*version|Note:|Reading|Preparing|Printing|ProgramClass:|Searching|'
-      r'jar \[|\d+ class path entries checked|.*:.*(?:MANIFEST\.MF|\.empty)')
+      r'jar \[|\d+ class path entries checked')
 
   def __init__(self):
     self._last_line_ignored = False
@@ -128,8 +128,11 @@ class ProguardCmdBuilder(object):
     for optimization in self._disabled_optimizations:
       cmd += [ '-optimizations', '!' + optimization ]
 
+    # Filter out META-INF files to avoid warnings about multiple inputs having
+    # the same files.
     cmd += [
-      '-injars', ':'.join(self._injars)
+        '-injars',
+        ':'.join('{}(!META-INF/**,!.empty)'.format(x) for x in self._injars)
     ]
 
     for config_file in self._configs: