[Cronet] Use gn desc to find third party licenses on Android.

tools/licenses.py

Index: tools/licenses.py
diff --git a/tools/licenses.py b/tools/licenses.py
index 9f33ffb8450ef0e440658c997302b3c55a904bf1..d4767fdd4c2f619f98389779df512d2b3d9332d2 100755
--- a/tools/licenses.py
+++ b/tools/licenses.py
@@ -493,7 +493,8 @@ def GetThirdPartyDepsFromGNDepsOutput(gn_deps):
     third_party_deps = set()
     for build_dep in gn_deps.split():
         m = re.search(r'^(.+/third_party/[^/]+)/(.+/)?BUILD\.gn$', build_dep)
-        if m:
+        # TODO(phajdan): Consider using PRUNE_PATHS to filter unwanted deps.

[Paweł Hajdan Jr., 2017/06/30 07:16:05]

Why does this TODO add me? It should add the person who has more context... you?
;-)

[mef, 2017/06/30 12:38:40]

I'll be happy to leave it as is or use PRUNE_PATHS if that makes sense, which I
don't know. 
Do you know, who is a proper person to ask?

The technical difficulty I ran into here is that PRUNE_PATHS contain relative
paths, but |build_dep| contains the absolute one, so naive 'build_dep in
PRUNE_PATHS' doesn't work.

[mef, 2017/06/30 14:31:45]

I've played with relpath and PRUNE_PATHS and it looks ugly.
The problematic directory is 'build/secondary/third_party/android_tools' so
naive check for it being in PRUNE_PATHS doesn't work.

I think that current check is reasonably good and can stay. WDYT?
 

+        if m and not os.path.join("secondary", "third_party") in build_dep:
             third_party_deps.add(m.group(1))
     return third_party_deps