Port custom_tabs_client from GYP to GN

build/config/android/rules.gni

Index: build/config/android/rules.gni
diff --git a/build/config/android/rules.gni b/build/config/android/rules.gni
index dee611624e988b146cb2f20d741a4b8c73b322b2..e009056c779cf4992005774c8316b8d3becc3339 100644
--- a/build/config/android/rules.gni
+++ b/build/config/android/rules.gni
@@ -1105,6 +1105,7 @@ template("android_java_prebuilt") {
 # Variables
 #   android_manifest: Path to AndroidManifest.xml.
 #   android_manifest_dep: Target that generates AndroidManifest (if applicable)
+#   chromium_code: If true, extra analysis warning/errors will be enabled.
 #   data_deps: List of dependencies needed at runtime. These will be built but
 #     won't change the generated .apk in any way (in fact they may be built
 #     after the .apk is).
@@ -1383,6 +1384,10 @@ template("android_apk") {
 
     android_manifest = _android_manifest
     chromium_code = true
+    if (defined(invoker.chromium_code)) {
+      chromium_code = invoker.chromium_code
+    }
+
     if (defined(invoker.java_files)) {
       java_files = invoker.java_files
     } else if (defined(invoker.DEPRECATED_java_in_dir)) {
@@ -1799,7 +1804,9 @@ template("unittest_apk") {
     if (defined(invoker.deps)) {
       deps += invoker.deps
     }
-    data_deps = [ "//tools/android/md5sum" ]
+    data_deps = [
+      "//tools/android/md5sum",
+    ]
     if (host_os == "linux") {
       data_deps += [ "//tools/android/forwarder2" ]
     }