[Lorenz] Adapt graph generation for older checkouts

In older checkouts, the .javac.jar is in gen/ rather than obj/

Change-Id: I1a149fd02e463b1fabd2be87e584bb0f9c759c19
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2518700Reviewed-by: Mohamed Heikal <mheikal@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824907}

tools/android/dependency_analysis/generate_json_dependency_graph.py

@@ -14,6 +14,7 @@ import os
 from typing import List, Tuple
 
 import class_dependency
+import git_utils
 import package_dependency
 import serialization
 import subprocess_utils
@@ -105,8 +106,8 @@ def _run_gn_desc_list_dependencies(build_output_dir: str, target: str,
 JarTargetList = List[Tuple[str, pathlib.Path]]
 
 
-def list_original_targets_and_jars(gn_desc_output: str,
-                                   build_output_dir: str) -> JarTargetList:
+def list_original_targets_and_jars(gn_desc_output: str, build_output_dir: str,
+                                   cr_position: int) -> JarTargetList:
     """Parses gn desc output to list original java targets and output jar paths.
 
     Returns a list of tuples (build_target: str, jar_path: str), where:
@@ -121,19 +122,27 @@ def list_original_targets_and_jars(gn_desc_output: str,
             continue
         build_target = build_target_line.strip()
         original_build_target = build_target.replace('__compile_java', '')
-        jar_path = _get_jar_path_for_target(build_output_dir, build_target)
+        jar_path = _get_jar_path_for_target(build_output_dir, build_target,
+                                            cr_position)
         jar_tuples.append((original_build_target, jar_path))
     return jar_tuples
 
 
-def _get_jar_path_for_target(build_output_dir: str, build_target: str) -> str:
+def _get_jar_path_for_target(build_output_dir: str, build_target: str,
+                             cr_position: int) -> str:
+    if cr_position == 0:  # Not running on main branch, use current convention.
+        subdirectory = 'obj'
+    elif cr_position < 761560:  # crrev.com/c/2161205
+        subdirectory = 'gen'
+    else:
+        subdirectory = 'obj'
     """Calculates the output location of a jar for a java build target."""
     target_path, target_name = build_target.split(':')
     assert target_path.startswith('//'), \
         f'Build target should start with "//" but is: "{build_target}"'
     jar_dir = target_path[len('//'):]
     jar_name = target_name.replace('__compile_java', '.javac.jar')
-    return pathlib.Path(build_output_dir) / 'obj' / jar_dir / jar_name
+    return pathlib.Path(build_output_dir) / subdirectory / jar_dir / jar_name
 
 
 def main():
@@ -186,12 +195,15 @@ def main():
     # gn and git must be run from inside the git checkout.
     os.chdir(src_path)
 
+    cr_position_str = git_utils.get_last_commit_cr_position()
+    cr_position = int(cr_position_str) if cr_position_str else 0
+
     print('Getting list of dependency jars...')
     gn_desc_output = _run_gn_desc_list_dependencies(arguments.build_output_dir,
                                                     arguments.target,
                                                     arguments.gn_path)
     target_jars: JarTargetList = list_original_targets_and_jars(
-        gn_desc_output, arguments.build_output_dir)
+        gn_desc_output, arguments.build_output_dir, cr_position)
 
     print('Running jdeps...')
     # jdeps already has some parallelism

tools/android/dependency_analysis/generate_json_dependency_graph_unittest.py

@@ -51,9 +51,46 @@ class TestHelperFunctions(unittest.TestCase):
             generate_json_dependency_graph.class_is_interesting(
                 'java.lang.Object'))
 
-    def test_list_original_targets_and_jars(self):
+    def test_list_original_targets_and_jars_legacy(self):
         result = generate_json_dependency_graph.list_original_targets_and_jars(
-            GN_DESC_OUTPUT, 'out/Test')
+            GN_DESC_OUTPUT, 'out/Test', 761559)
+        # Before crrev.com/c/2161205, *.javac.jar were in gen/
+        self.assertEqual(len(result), 3)
+        self.assertEqual(
+            result[0],
+            ('//path/to/dep1:java',
+             pathlib.Path('out/Test/gen/path/to/dep1/java.javac.jar')))
+        self.assertEqual(
+            result[1],
+            ('//path/to/dep2:java',
+             pathlib.Path('out/Test/gen/path/to/dep2/java.javac.jar')))
+        self.assertEqual(
+            result[2],
+            ('//path/to/root:java',
+             pathlib.Path('out/Test/gen/path/to/root/java.javac.jar')))
+
+    def test_list_original_targets_and_jars_current(self):
+        # After crrev.com/c/2161205, *.javac.jar are in obj/
+        result = generate_json_dependency_graph.list_original_targets_and_jars(
+            GN_DESC_OUTPUT, 'out/Test', 761560)
+        self.assertEqual(len(result), 3)
+        self.assertEqual(
+            result[0],
+            ('//path/to/dep1:java',
+             pathlib.Path('out/Test/obj/path/to/dep1/java.javac.jar')))
+        self.assertEqual(
+            result[1],
+            ('//path/to/dep2:java',
+             pathlib.Path('out/Test/obj/path/to/dep2/java.javac.jar')))
+        self.assertEqual(
+            result[2],
+            ('//path/to/root:java',
+             pathlib.Path('out/Test/obj/path/to/root/java.javac.jar')))
+
+    def test_list_original_targets_and_jars_branch(self):
+        # A branch without Commit-Cr-Position should be considered modern
+        result = generate_json_dependency_graph.list_original_targets_and_jars(
+            GN_DESC_OUTPUT, 'out/Test', 0)
         self.assertEqual(len(result), 3)
         self.assertEqual(
             result[0],