Reland "[Cronet] Build maven modules and test by building sample app …

…with gradle"

This is a reland of 10f4dd8996fe4a028ee2aa61cdf84ad4080ef31c

I disabled the gradle build when !use_platform_icu_alternatives so Android bots
continue to build successfully.  I also moved cronet_maven/ output directory to
cronet/maven/ so it can be uploaded by the bots.

Original change's description:
> [Cronet] Build maven modules and test by building sample app with gradle
>
> This change builds maven modules for Cronet.
> Each maven module includes:
>   1. POM file defining module and listing dependent modules
>   2. Jars
>   3. Proguard files (optional)
>   4. Native libraries (optional)
>   5. Resources (optional)
>   6. Javadocs (optional)
> We build four maven modules:
>   1. cronet-api: the Cronet API
>   2. cronet-embedded: the Cronet native implementation
>   3. cronet-fallback: the Cronet fallback implementation
>   4. cronet-common: Cronet implementation in common with #3 and #4
>
> To test the maven modules, this change builds the Cronet sample app using gradle.
> You can install and run the resulting app by:
>   ninja -C out/Debug cronet_maven_test_build
>   adb install -r out/Debug/cronet_maven/test/build/outputs/apk/debug/test-debug.apk
>   adb install -r out/Debug/cronet_maven/test/build/outputs/apk/androidTest/debug/test-debug-androidTest.apk
>   adb shell am instrument -w org.chromium.cronet_sample_apk.test/android.support.test.runner.AndroidJUnitRunner
>
> Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
> Change-Id: I5ed27e86f3e01dc3a6441ab449bbe942553343af
> Reviewed-on: https://chromium-review.googlesource.com/998019
> Commit-Queue: Paul Jensen <[email protected]>
> Reviewed-by: Andrei Kapishnikov <[email protected]>
> Reviewed-by: Eric Stevenson <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#554608}

Change-Id: Ieba6842b48d0b8e97ca1dc6686080cb31a87ed95
Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet

[email protected]
Eric already approved the build/ change in https://chromium-review.googlesource.com/998019

Change-Id: Ieba6842b48d0b8e97ca1dc6686080cb31a87ed95
Reviewed-on: https://chromium-review.googlesource.com/1037723
Commit-Queue: Paul Jensen <[email protected]>
Reviewed-by: Eric Stevenson <[email protected]>
Reviewed-by: Andrei Kapishnikov <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#555157}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 5ff415959d5ef4d105cda4cd4fe36f06107f54b9

config/android/rules.gni

@@ -1510,6 +1510,7 @@ if (enable_java_templates) {
   #   proguard_configs: List of proguard configs (optional).
   #   android_manifest: Path to AndroidManifest.xml (optional).
   #   native_libraries: list of native libraries (optional).
+  #   direct_deps_only: Do not recurse on deps. (optional, defaults false).
   #
   # Example
   #   dist_aar("my_aar") {
@@ -1524,6 +1525,9 @@ if (enable_java_templates) {
       _deps = invoker.deps
     }
 
+    _direct_deps_only =
+        defined(invoker.direct_deps_only) && invoker.direct_deps_only
+
     _build_config = "$target_gen_dir/$target_name.build_config"
     _build_config_target_name = "${target_name}__build_config"
 
@@ -1566,11 +1570,15 @@ if (enable_java_templates) {
         rebase_path(depfile, root_build_dir),
         "--output",
         rebase_path(invoker.output, root_build_dir),
-        "--jars=@FileArg($_rebased_build_config:deps_info:javac_full_classpath)",
         "--dependencies-res-zips=@FileArg($_rebased_build_config:resources:dependency_zips)",
         "--r-text-files=@FileArg($_rebased_build_config:resources:extra_r_text_files)",
         "--proguard-configs=@FileArg($_rebased_build_config:deps_info:proguard_all_configs)",
       ]
+      if (_direct_deps_only) {
+        args += [ "--jars=@FileArg($_rebased_build_config:javac:classpath)" ]
+      } else {
+        args += [ "--jars=@FileArg($_rebased_build_config:deps_info:javac_full_classpath)" ]
+      }
       if (defined(invoker.android_manifest)) {
         args += [
           "--android-manifest",