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

testing/chromoting/integration_tests.gyp

Index: testing/chromoting/integration_tests.gyp
diff --git a/testing/chromoting/integration_tests.gyp b/testing/chromoting/integration_tests.gyp
index 40c80eeed89d5295509cd905b9b420c859b8f693..a7d733263c8232832329d7728b97c2e59280dbe9 100644
--- a/testing/chromoting/integration_tests.gyp
+++ b/testing/chromoting/integration_tests.gyp
@@ -47,6 +47,31 @@
           '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'
       ],
     }],