Landmines support to ease clobbering builds

Landmines is a feature used in Chromium that makes it possible to
clobber the build output directory when needed. Example scenarios
are when compiler/tool/infrastructure changes require a full rebuild.
This is mainly to ease clobbering on all bots, but will also ensure
developers don't have to waste time on figuring out what's wrong
(or rely on reading PSA e-mails announcing when such manual action
is required).

This CL depends on https://codereview.chromium.org/1407733002/
being landed and rolled into DEPS first.

BUG=5077
R=kjellander@chromium.org, machenbach@chromium.org

Review URL: https://codereview.webrtc.org/1402923003 .

Cr-Commit-Position: refs/heads/master@{#10287}
diff --git a/DEPS b/DEPS
index bd2d0b0..a61126a 100644
--- a/DEPS
+++ b/DEPS
@@ -71,6 +71,21 @@
     'action': ['python', 'src/setup_links.py'],
   },
   {
+    # This clobbers when necessary (based on get_landmines.py). It should be
+    # an early hook but it will need to be run after syncing Chromium and
+    # setting up the links, so the script actually exists.
+    'name': 'landmines',
+    'pattern': '.',
+    'action': [
+        'python',
+        'src/build/landmines.py',
+        '--landmine-scripts',
+        'src/webrtc/build/get_landmines.py',
+        '--src-dir',
+        'src',
+    ],
+  },
+  {
      # Pull sanitizer-instrumented third-party libraries if requested via
      # GYP_DEFINES. This could be done as part of sync_chromium.py above
      # but then we would need to run all the Chromium hooks each time,