Update from https://crrev.com/302630

build/landmines.py

Index: build/landmines.py
diff --git a/build/landmines.py b/build/landmines.py
index 96bc4854e1fe1613d06f91eca809b83fdd8c431f..2ddf346edd801603b1f9a8dc06242cdfdd119727 100755
--- a/build/landmines.py
+++ b/build/landmines.py
@@ -43,7 +43,12 @@ def get_build_dir(build_tool, is_iphone=False):
   if build_tool == 'xcode':
     ret = os.path.join(SRC_DIR, 'xcodebuild')
   elif build_tool in ['make', 'ninja', 'ninja-ios']:  # TODO: Remove ninja-ios.
-    ret = os.path.join(SRC_DIR, os.environ.get('CHROMIUM_OUT_DIR', 'out'))
+    if ('CHROMIUM_OUT_DIR' not in os.environ and
+        'output_dir' in landmine_utils.gyp_generator_flags()):
+      output_dir = landmine_utils.gyp_generator_flags()['output_dir']
+    else:
+      output_dir = os.environ.get('CHROMIUM_OUT_DIR', 'out')
+    ret = os.path.join(SRC_DIR, output_dir)
   else:
     raise NotImplementedError('Unexpected GYP_GENERATORS (%s)' % build_tool)
   return os.path.abspath(ret)