Add --allow-downgrade argument for incremental installer.

build/android/incremental_install/installer.py

Index: build/android/incremental_install/installer.py
diff --git a/build/android/incremental_install/installer.py b/build/android/incremental_install/installer.py
index 421318cf3937073fda112c9e591633cc9ad09604..6c429118a018554ff5ce0122191ec9f060079da6 100755
--- a/build/android/incremental_install/installer.py
+++ b/build/android/incremental_install/installer.py
@@ -86,7 +86,8 @@ def Uninstall(device, package, enable_device_cache=False):
 
 def Install(device, apk, split_globs=None, native_libs=None, dex_files=None,
             enable_device_cache=False, use_concurrency=True,
-            show_proguard_warning=False, permissions=()):
+            show_proguard_warning=False, permissions=(),
+            allow_downgrade=True):
   """Installs the given incremental apk and all required supporting files.
 
   Args:
@@ -119,9 +120,11 @@ def Install(device, apk, split_globs=None, native_libs=None, dex_files=None,
       for split_glob in split_globs:
         splits.extend((f for f in glob.glob(split_glob)))
       device.InstallSplitApk(apk, splits, reinstall=True,
-                             allow_cached_props=True, permissions=permissions)
+                             allow_cached_props=True, permissions=permissions,
+                             allow_downgrade=allow_downgrade)
     else:
-      device.Install(apk, reinstall=True, permissions=permissions)
+      device.Install(apk, reinstall=True, permissions=permissions,
+                     allow_downgrade=allow_downgrade)
     install_timer.Stop(log=False)
 
   # Push .so and .dex files to the device (if they have changed).
@@ -272,6 +275,12 @@ def main():
                       default=0,
                       action='count',
                       help='Verbose level (multiple times for more)')
+  parser.add_argument('--disable-downgrade',
+                      action='store_false',
+                      default=True,
+                      dest='allow_downgrade',
+                      help='Disable install of apk with lower version number'
+                           'than the version already on the device.')
 
   args = parser.parse_args()
 
@@ -300,7 +309,8 @@ def main():
     Install(device, apk, split_globs=args.splits, native_libs=args.native_libs,
             dex_files=args.dex_files, enable_device_cache=args.cache,
             use_concurrency=args.threading,
-            show_proguard_warning=args.show_proguard_warning)
+            show_proguard_warning=args.show_proguard_warning,
+            allow_downgrade=args.allow_downgrade)
 
 
 if __name__ == '__main__':