Default chromium_code = false for Android targets within third_party

This affects the following:
  //third_party/jmake:jmake
  //third_party/jsr-305:jsr_305_javalib
  //third_party/gif_player:gif_player_java
  //third_party/leakcanary:leakcanary_noop_java

BUG=621774
TBR=yusufo

Review-Url: https://codereview.chromium.org/2103273002
Cr-Commit-Position: refs/heads/master@{#402926}

build/config/android/internal_rules.gni

@@ -1983,9 +1983,25 @@ if (enable_java_templates) {
 
     # Don't enable coverage, lint, findbugs unless the target has some
     # non-generated files.
-    _chromium_code = defined(invoker.java_files) && invoker.java_files != []
     if (defined(invoker.chromium_code)) {
       _chromium_code = invoker.chromium_code
+    } else {
+      _chromium_code = defined(invoker.java_files) && invoker.java_files != []
+      if (_chromium_code) {
+        # Make chromium_code = false be the default for targets within
+        # third_party which contain no chromium-namespaced java files.
+        set_sources_assignment_filter([ "*\bthird_party\b*" ])
+        sources = [
+          get_label_info(":$target_name", "dir"),
+        ]
+        if (sources == []) {
+          set_sources_assignment_filter([ "*\bchromium\b*" ])
+          sources = invoker.java_files
+          _chromium_code = invoker.java_files != sources
+        }
+        set_sources_assignment_filter([])
+        sources = []
+      }
     }
 
     _emma_never_instrument = !_chromium_code

third_party/custom_tabs_client/BUILD.gn

@@ -38,6 +38,7 @@ android_library("custom_tabs_client_shared_lib") {
   deps = [
     ":custom_tabs_support_lib",
   ]
+  chromium_code = true
 }
 
 android_library("custom_tabs_support_lib") {
@@ -54,6 +55,7 @@ android_library("custom_tabs_support_lib") {
     "//third_party/android_tools:android_support_v13_java",
   ]
   srcjar_deps = [ ":chrome_custom_tabs_service_aidl" ]
+  chromium_code = true
 }
 
 android_aidl("chrome_custom_tabs_service_aidl") {