Android: Don't fail builds for warnings when is_debug=true

Adds GN arg: java_warnings_as_errors = !is_java_debug

And sets the arg on our trybot that runs errorprone.

TBR=jbudorick  # Expedite fixing local dev flow.

Bug: 1029357
Change-Id: I817931328dc56ca67d7047d711fa60ba38e21fd6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1943014
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720074}

build/android/gyp/javac.py

@@ -477,6 +477,10 @@ def _ParseOptions(argv):
       '--enable-errorprone',
       action='store_true',
       help='Enable errorprone checks')
+  parser.add_option(
+      '--warnings-as-errors',
+      action='store_true',
+      help='Treat all warnings as errors.')
   parser.add_option('--jar-path', help='Jar output path.')
   parser.add_option(
       '--javac-arg',
@@ -550,6 +554,8 @@ def main(argv):
       errorprone_flags.append('-Xep:{}:OFF'.format(warning))
     for warning in ERRORPRONE_WARNINGS_TO_ERROR:
       errorprone_flags.append('-Xep:{}:ERROR'.format(warning))
+    if not options.warnings_as_errors:
+      errorprone_flags.append('-XepAllErrorsAsWarnings')
     javac_cmd += ['-XDcompilePolicy=simple', ' '.join(errorprone_flags)]
 
   if options.java_version:
@@ -561,7 +567,7 @@ def main(argv):
     # Android's boot jar doesn't contain all java 8 classes.
     options.bootclasspath.append(build_utils.RT_JAR_PATH)
 
-  if options.chromium_code:
+  if options.warnings_as_errors:
     javac_cmd.extend(['-Werror'])
   else:
     # XDignore.symbol.file makes javac compile against rt.jar instead of

build/config/android/config.gni

@@ -224,6 +224,9 @@ if (is_android || is_chromeos) {
 
     # Use hashed symbol names to reduce JNI symbol overhead.
     use_hashed_jni_names = !is_java_debug
+
+    # For local development, it's nice to not fail builds on warnings.
+    java_warnings_as_errors = !is_java_debug
   }
 
   # Path to where selected build variables are written to.

build/config/android/internal_rules.gni

@@ -968,7 +968,6 @@ if (enable_java_templates) {
             rebase_path(invoker.build_config, root_build_dir)
         args += [
           "--srcjars=@FileArg($_rebased_build_config:gradle:bundled_srcjars)",
-          "--can-fail-build",
         ]
         if (invoker.requires_android) {
           args += [
@@ -976,6 +975,9 @@ if (enable_java_templates) {
             "--resource-sources=@FileArg($_rebased_build_config:deps_info:owned_resources_zips)",
           ]
         }
+        if (java_warnings_as_errors) {
+          args += [ "--can-fail-build" ]
+        }
       }
 
       if (defined(invoker.manifest_package)) {
@@ -2820,6 +2822,9 @@ if (enable_java_templates) {
       }
       if (_chromium_code) {
         args += [ "--chromium-code=1" ]
+        if (java_warnings_as_errors) {
+          args += [ "--warnings-as-errors" ]
+        }
       }
       if (defined(invoker.jar_excluded_patterns)) {
         args += [ "--jar-info-exclude-globs=${invoker.jar_excluded_patterns}" ]

tools/mb/mb_config.pyl

@@ -1120,7 +1120,7 @@
     ],
 
     'android_debug_trybot_compile_only': [
-      'android', 'debug_trybot', 'compile_only',
+      'android', 'debug_trybot', 'compile_only', 'java_warnings_as_errors',
     ],
 
     'android_debug_trybot_compile_only_arm64_fastbuild': [
@@ -2280,6 +2280,10 @@
       'gn_args': 'skip_archive_compression=false',
     },
 
+    'java_warnings_as_errors': {
+      'gn_args': ('java_warnings_as_errors=true'),
+    },
+
     'enable_vulkan': {
       'gn_args': 'enable_vulkan=true',
     },