Auto merge of #18680 - MortimerGoro:android_flavors, r=larsbergstrom

Implement Gradle flavors for Android VR compilations

<!-- Please describe your changes on the following line: -->

This PR adds support to easily generate Android VR builds. Rust/Java VR dependencies are not added by default.

Default build (No VR support)
```
./mach build --release --android
./mach package --release --android
./mach install --release --android
```

GoogleVR builds (e.g. Daydream)
```
./mach build --release --android --features googlevr
./mach package --release --android --flavor googlevr
./mach install --release --android
```

OculusVR builds (e.g. Gear VR)
```
./mach build --release --android --features oculusvr
./mach package --release --android --flavor oculusvr
./mach install --release --android
```

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/18680)
<!-- Reviewable:end -->

python/servo/build_commands.py

@@ -309,6 +309,11 @@ class MachCommands(CommandBase):
             env['CPPFLAGS'] = ' '.join(["--sysroot", env['ANDROID_SYSROOT']])
             env["CMAKE_ANDROID_ARCH_ABI"] = self.config["android"]["lib"]
             env["CMAKE_TOOLCHAIN_FILE"] = path.join(self.android_support_dir(), "toolchain.cmake")
+            # Set output dir for gradle aar files
+            aar_out_dir = self.android_aar_dir()
+            if not os.path.exists(aar_out_dir):
+                os.makedirs(aar_out_dir)
+            env["AAR_OUT_DIR"] = aar_out_dir
 
         cargo_binary = "cargo" + BIN_SUFFIX
 

python/servo/command_base.py

@@ -551,6 +551,9 @@ class CommandBase(object):
     def android_build_dir(self, dev):
         return path.join(self.get_target_dir(), self.config["android"]["target"], "debug" if dev else "release")
 
+    def android_aar_dir(self):
+        return path.join(self.context.topdir, "target", "android_aar")
+
     def handle_android_target(self, target):
         if target == "arm-linux-androideabi":
             self.config["android"]["platform"] = "android-18"

python/servo/package_commands.py

@@ -180,7 +180,10 @@ class PackageCommands(CommandBase):
     @CommandArgument('--target', '-t',
                      default=None,
                      help='Package for given target platform')
-    def package(self, release=False, dev=False, android=None, debug=False, debugger=None, target=None):
+    @CommandArgument('--flavor', '-f',
+                     default=None,
+                     help='Package using the given Gradle flavor')
+    def package(self, release=False, dev=False, android=None, debug=False, debugger=None, target=None, flavor=None):
         env = self.build_env()
         if android is None:
             android = self.config["build"]["android"]
@@ -206,7 +209,11 @@ class PackageCommands(CommandBase):
             else:
                 build_mode = "Release"
 
-            task_name = "assemble" + build_type + build_mode
+            flavor_name = "Main"
+            if flavor is not None:
+                flavor_name = flavor.title()
+
+            task_name = "assemble" + flavor_name + build_type + build_mode
             try:
                 with cd(path.join("support", "android", "apk")):
                     subprocess.check_call(["./gradlew", "--no-daemon", task_name], env=env)