Add functionality to download files from GCS, and include them in the Chromoting isolate.

testing/chromoting/integration_tests.gyp

 # Copyright (c) 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'run_multi_machine_tests%': '0',
   },
 
   'conditions': [
@@ skipping 29 matching lines @@
       ],
       'targets': [
         {
           'target_name': 'chromoting_integration_tests_run',
           'includes': [
             './dependencies.gypi',
           ],
           'sources': [
             'chromoting_integration_tests.isolate',
           ],
+          'actions': [
+            {
+              'action_name': 'download_test_files',
+              'variables': {
+                'dl_files_script': './download_test_files.py',
+                'input_files': './test_files.txt',

[joedow, 2015/07/13 19:10:12]

Does it make sense to have a single file which has all of the files needed?  If
chromoting and app remoting both have their own set of files, I'm assuming that
we wouldn't use the same input_file.  Could we just use 'inputs' below and list
the files their (along with a bucket as a parameter to the download script)?

[anandc, 2015/07/14 01:03:07]

Good suggestion.
I tried listing the files as a variable here and also in 'inputs' below. In the
former case, there is an error during runhooks, and the latter there is an error
during the build-step. 
The error message in both cases is like:

ninja: error:
'../../testing/chromoting/gs:/chrome-chromoting-test-data/integration_tests/input/test_accounts.json
gs:/chrome-chromoting-test-data/test.txt', needed by '../../testing/chromoting',
missing and no known rule to make it

It looks like GYP expects whatever is specified here to already exist on the
client machine from where the build is run.

So, keeping this to point to an existing file.
Changed its name to say chromoting_*, so that we may have different files
downloaded depending on the target.

I also changed the name of this variable, because input_files is not entirely
correct/clear.

+                'output_folder': './',
+              },
+              'inputs': [
+                '<(input_files)',
+              ],
+              'outputs': [
+                '<(output_folder)',
+              ],
+              'action': [
+                'python',
+                '<(dl_files_script)',
+                '--input_files',
+                '<(input_files)',
+                '--output_folder',
+                '<(output_folder)',
+              ],
+              'message': 'Downloading required Remoting test files.',

[joedow, 2015/07/13 19:10:12]

I think message should say "Downloading required chromoting test files" since
this only applies to the chromoting target.

[anandc, 2015/07/14 01:03:07]

Done.

+            },
+          ],
         },  # target_name: 'chromoting_integration_tests_run'
       ],
     }],
   ],
 }