Landmines support to ease clobbering builds

DEPS

 # This file contains dependencies for WebRTC that are not shared with Chromium.
 # If you wish to add a dependency that is present in Chromium's src/DEPS or a
 # directory from the Chromium checkout, you should add it to setup_links.py
 # instead.
 
 vars = {
   'extra_gyp_flag': '-Dextra_gyp_flag=0',
   'chromium_git': 'https://chromium.googlesource.com',
   'chromium_revision': 'b8ff10300d8a3eed9a7e7713c2ef0606d95a42f2',
 }
@@ skipping 30 matching lines @@
   '+talk',
   '+testing',
   '+third_party',
   '+unicode',
   '+webrtc',
   '+vpx',
 ]
 
 hooks = [
   {
+    # This clobbers when necessary (based on get_landmines.py). It must be the
+    # first hook so that other things that get/generate into the output
+    # directory will not subsequently be clobbered.
+    'name': 'landmines',
+    'pattern': '.',
+    'action': [
+        'python',
+        'src/build/landmines.py',
+        '--landmine-scripts',
+        'src/webrtc/build/get_landmines.py',
+        '--src-dir',
+        'src',

[Michael Achenbach, 2015/10/15 07:38:20]

How is that different to the old default value SRC_DIR in chromium's landmines
script?

Why is only one trybot failing and not all? Did they sync do different chromium
versions?

[kjellander_chromium, 2015/10/15 10:51:41]

I understand your confusion, but since we're using symlinks the actual script
location is chromium/src/build/ so when it tries to lookup the root, it will
become chromium/src and thus put the .landmines file in there, which itself is
probably OK, but I wanted to keep things clean.
It's because we have pools of machines shared between the trybots to optimize
the throughput. Not all machines had performed a build on all their checkouts
yet (which is one of the large disadvantages with that approach).

+    ],
+  },
+  {
     # Check for legacy named top-level dir (named 'trunk').
     'name': 'check_root_dir_name',
     'pattern': '.',
     'action': ['python','-c',
                ('import os,sys;'
                 'script = os.path.join("trunk","check_root_dir.py");'
                 '_ = os.system("%s %s" % (sys.executable,script)) '
                 'if os.path.exists(script) else 0')],
   },
   {
@@ skipping 31 matching lines @@
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     'name': 'gyp',
     'pattern': '.',
     'action': ['python', 'src/webrtc/build/gyp_webrtc',
                Var('extra_gyp_flag')],
   },
 ]