Add shared preference file modification option to instrumentation test runner

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 08ec868e2b55155acc85e226f9088fae6134bda1..932a2804b9815cd8e40cd24b5cfb082a9c45a664 100755
--- a/build/android/test_runner.py
+++ b/build/android/test_runner.py
@@ -400,6 +400,22 @@ def AddInstrumentationTestOptions(parser):
   group.add_argument('--store-tombstones', dest='store_tombstones',
                      action='store_true',
                      help='Add tombstones in results if crash.')
+  group.add_argument('--shared-prefs-file', dest='shared_prefs_file',

[jbudorick, 2017/02/15 22:38:42]

nit: add type=os.path.realpath.

[bsheedy, 2017/02/15 22:54:52]

I initially did this, but then it appends the current directory to the front,
e.g. if we're in //third_party and run the test runner with --shared-prefs-file
chrome/android/example.json, the path will end up as
//third_party/chrome/android/example.json. If it's fine to have a relative path
from wherever the script is being run instead of a path relative to the source
root directory, then I can make this change.

[jbudorick, 2017/02/16 02:57:09]

Yeah, that's fine. I think you're more likely to run it w/ a path relative to
your current directory than one relative to src if you're using a relative
directory. The recipes will give it an absolute path.

(realpath also handles symlinks, which is a nice bonus.)

[bsheedy, 2017/02/16 18:04:50]

Done.

+                     help='The path from the source root directory '
+                          'to a file containing JSON list of shared '
+                          'preference files to edit and how to do '
+                          'so. Example list: '
+                          '[{'

[jbudorick, 2017/02/15 22:38:42]

nit: how does this appear in the actual --help text? It's nicely formatted here,
but I'm not sure that'll carry over.

[bsheedy, 2017/02/15 22:54:52]

It doesn't look nicely formatted when --help is used. Manually formatting with
newlines doesn't work unless you set an option in the ArgumentParser that says
not to do any automatic formatting, but then all the other help texts become
long lines of text. I can just remove the example if that's preferable to a
not-so-nicely-formatted example.

[jbudorick, 2017/02/16 02:57:08]

eh, I think it's ok for now.

[bsheedy, 2017/02/16 18:04:50]

Done.

+                          '  "package": "com.package.example",'
+                          '  "filename": "ExampleSettings.xml",'
+                          '  "set": {'
+                          '    "boolean_key_in_xml": true,'
+                          '    "string_key_in_xml": "string_value"'
+                          '  },'
+                          '  "remove": ['
+                          '    "key_in_xml_to_remove"'
+                          '  ]'
+                          '}]')
 
   AddCommonOptions(parser)
   AddDeviceOptions(parser)