[Android] Run lint using a cache in the output directory.

build/android/BUILD.gn

Index: build/android/BUILD.gn
diff --git a/build/android/BUILD.gn b/build/android/BUILD.gn
index 5428875d2ad04ad4658142bb7c41ce7bf610197f..bd0459f6f48b54eae478479130f708518fb396a2 100644
--- a/build/android/BUILD.gn
+++ b/build/android/BUILD.gn
@@ -7,6 +7,42 @@ import("//third_party/ijar/ijar.gni")
 
 sun_tools_jar_path = "$root_gen_dir/sun_tools_jar/tools.jar"
 
+# Create or update the API versions cache if necessary by running a
+# functionally empty lint task. This prevents racy creation of the
+# cache while linting java targets in android_lint.
+action("prepare_lint_cache") {
+  cache_dir = "${root_out_dir}/lint_cache"

[agrieve, 2016/03/19 00:12:53]

nit: can we call it "android_lint_cache"?

[jbudorick, 2016/03/19 00:57:42]

Done.

+  depfile = "${cache_dir}/prepare_lint_cache.d"
+  manifest_file = "//build/android/AndroidManifest.xml"

[agrieve, 2016/03/19 00:12:53]

nit: add _ prefix to these two and cache_dir so they don't look like they belong
to action()

[jbudorick, 2016/03/19 00:57:42]

Done.

+  result_file = "${cache_dir}/result.xml"
+  script = "//build/android/gyp/lint.py"
+
+  inputs = [
+    "${android_sdk_root}/platform-tools/api/api-versions.xml",
+  ]
+  outputs = [
+    depfile,
+  ]
+  args = [
+    "--build-tools-version",
+    android_sdk_build_tools_version,
+    "--cache-dir",
+    rebase_path(cache_dir, root_build_dir),
+    "--depfile",
+    rebase_path(depfile, root_build_dir),
+    "--lint-path",
+    "$rebased_android_sdk_root/tools/lint",
+    "--manifest-path",
+    rebase_path(manifest_file, root_build_dir),
+    "--product-dir",
+    ".",
+    "--result-path",
+    rebase_path(result_file, root_build_dir),
+    "--silent",
+    "--enable",
+  ]
+}
+
 action("find_sun_tools_jar") {
   script = "//build/android/gyp/find_sun_tools_jar.py"
   depfile = "$target_gen_dir/$target_name.d"