Android gtest runner: Add --enable-concurrent-adb flag

build/android/test_runner.py

Index: build/android/test_runner.py
diff --git a/build/android/test_runner.py b/build/android/test_runner.py
index 955e09b4d928428d6109babc4b9ba8e11500eaa4..01d45c081352803f35709e56205e8ee2ade3c334 100755
--- a/build/android/test_runner.py
+++ b/build/android/test_runner.py
@@ -190,6 +190,9 @@ def AddDeviceOptions(parser):
                      help='Cache device state to disk between runs')
   group.add_argument('--incremental-install', action='store_true',
                      help='Use an _incremental apk.')
+  group.add_argument('--enable-concurrent-adb', action='store_true',
+                     help='Run multiple adb commands at the same time, even '
+                          'for the same device.')
 
 
 def AddGTestOptions(parser):