generate_gradle.py: Don't enable --all when --target is passed

This allows creating smaller projects again.

Change-Id: Id4bb02232d7e7430b1bf9228c4359e66b40b2793
Reviewed-on: https://chromium-review.googlesource.com/858596
Commit-Queue: agrieve <agrieve@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#528350}

build/android/gradle/generate_gradle.py

@@ -770,7 +770,11 @@ def main():
       args.canary)
   logging.warning('Creating project at: %s', generator.project_dir)
 
-  args.all = args.all or not args.split_projects
+  # Generate for "all targets" by default when not using --split-projects (too
+  # slow), and when no --target has been explicitly set. "all targets" means all
+  # java targets that are depended on by an apk or java_binary (leaf
+  # java_library targets will not be included).
+  args.all = args.all or (not args.split_projects and not args.targets)
 
   targets_from_args = set(args.targets or _DEFAULT_TARGETS)
   if args.extra_targets: