Attempt #4 of "Add test directory -> monorail component metadata to test"

This is a reland of 39b25a5f892c66354301b0bd505d45d5a38e6e74; the
root problem seems to have been trying to run `dirmd` on Win7,
and we've upgraded the Win7 builders to be Win10, so in theory
we won't have this issue this time.

Original change's description:
> Add test directory -> monorail component metadata to test invocations.
>
> The new ResultDB system has the ability to associate test results with
> Monorail components and teams, but in order to do that, we need to
> upload the mapping information contained in the testing/DIR_METADATA
> files along with the test results.
>
> This CL adds a gclient hook to generate the metadata in a
> ResultDB-friendly format that can be accessed by `rdb` and uploaded
> as part of a test invocation, and makes the generated data a
> dependency of the bin/run_* test scripts, to ensure that every
> test invocation will have the data.
>
> Change-Id: I83dcf7f460b6fbd1d4c23616d972510712019148
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2568896
> Commit-Queue: Dirk Pranke <[email protected]>
> Reviewed-by: Chan Li <[email protected]>
> Reviewed-by: Nodir Turakulov <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#861612}

Bug: 1191087
Change-Id: I767fcbfb295723444902cfae27e25398df98b5d9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2785124
Reviewed-by: Dirk Pranke <[email protected]>
Reviewed-by: Chan Li <[email protected]>
Commit-Queue: Dirk Pranke <[email protected]>
Cr-Commit-Position: refs/heads/master@{#866323}
diff --git a/DEPS b/DEPS
index 833b563..3fd3ecb 100644
--- a/DEPS
+++ b/DEPS
@@ -4387,6 +4387,17 @@
     ],
   },
 
+  {
+    'name': 'Generate component metadata for tests',
+    'pattern': '.',
+    'action': [
+      'vpython',
+      'src/testing/generate_location_tags.py',
+      '--out',
+      'src/testing/location_tags.json',
+    ],
+  },
+
   # Download and initialize "vpython" VirtualEnv environment packages.
   {
     'name': 'vpython_common',