Fix zucchini gtests

We adjust the path to the test data, fix a DEX-dependent test to remove
the dependency on DEX support, and provide a workaround for an undefined
behavior potentially leading to false-positive test failures (see
https://issues.chromium.org/issues/429588215).
---
 components/zucchini/integration_test.cc          |  9 +++++++++
 components/zucchini/patch_read_write_unittest.cc | 11 +++++++++++
 components/zucchini/patch_utils_unittest.cc      | 14 ++++++++++++++
 3 files changed, 34 insertions(+)

diff --git a/components/zucchini/integration_test.cc b/components/zucchini/integration_test.cc
index b47cb73215c9..d87b197ea00e 100644
--- a/components/zucchini/integration_test.cc
+++ b/components/zucchini/integration_test.cc
@@ -23,10 +23,19 @@ namespace zucchini {
 base::FilePath MakeTestPath(const std::string& filename) {
   base::FilePath path;
   DCHECK(base::PathService::Get(base::DIR_SOURCE_ROOT, &path));
+#if !defined(MOZ_ZUCCHINI)
   return path.AppendASCII("components")
       .AppendASCII("zucchini")
       .AppendASCII("testdata")
       .AppendASCII(filename);
+#else
+  return path.AppendASCII("third_party")
+      .AppendASCII("zucchini")
+      .AppendASCII("tests")
+      .AppendASCII("gtest")
+      .AppendASCII("testdata")
+      .AppendASCII(filename);
+#endif  // !defined(MOZ_ZUCCHINI)
 }
 
 void TestGenApply(const std::string& old_filename,
diff --git a/components/zucchini/patch_read_write_unittest.cc b/components/zucchini/patch_read_write_unittest.cc
index 745616295f04..869138ce2df0 100644
--- a/components/zucchini/patch_read_write_unittest.cc
+++ b/components/zucchini/patch_read_write_unittest.cc
@@ -101,7 +101,12 @@ ByteVector CreateElementMatch() {
       0x02, 0,    0,   0,    // old_length
       0x03, 0,    0,   0,    // new_offset
       0x04, 0,    0,   0,    // new_length
+#if !defined(MOZ_ZUCCHINI)
       'D',  'E',  'X', ' ',  // exe_type = kExeTypeDex
+#else
+      // We need a supported exe_type value (we don't support DEX).
+      'N', 'o', 'O', 'p', // exe_type = kExeTypeNoOp
+#endif  // !defined(MOZ_ZUCCHINI)
       0x01, 0x00,            // element version
   };
 }
@@ -127,9 +132,15 @@ TEST(PatchTest, ParseSerializeElementMatch) {
   BufferSource buffer_source(data.data(), data.size());
   ElementMatch element_match = {};
   EXPECT_TRUE(patch::ParseElementMatch(&buffer_source, &element_match));
+#if !defined(MOZ_ZUCCHINI)
   EXPECT_EQ(kExeTypeDex, element_match.exe_type());
   EXPECT_EQ(kExeTypeDex, element_match.old_element.exe_type);
   EXPECT_EQ(kExeTypeDex, element_match.new_element.exe_type);
+#else
+  EXPECT_EQ(kExeTypeNoOp, element_match.exe_type());
+  EXPECT_EQ(kExeTypeNoOp, element_match.old_element.exe_type);
+  EXPECT_EQ(kExeTypeNoOp, element_match.new_element.exe_type);
+#endif  // !defined(MOZ_ZUCCHINI)
   EXPECT_EQ(0x1U, element_match.old_element.offset);
   EXPECT_EQ(0x2U, element_match.old_element.size);
   EXPECT_EQ(0x3U, element_match.new_element.offset);
diff --git a/components/zucchini/patch_utils_unittest.cc b/components/zucchini/patch_utils_unittest.cc
index 15b1c93367b0..757d4eb9ed52 100644
--- a/components/zucchini/patch_utils_unittest.cc
+++ b/components/zucchini/patch_utils_unittest.cc
@@ -51,6 +51,11 @@ void TestEncodeDecodeVarUInt(const std::vector<T>& data) {
 
 template <class T>
 void TestEncodeDecodeVarInt(const std::vector<T>& data) {
+#if defined(MOZ_ZUCCHINI)
+  // Workaround for https://issues.chromium.org/issues/429588215:
+  // signed integer overflow is undefined behavior, so we cast to unsigned.
+  using unsigned_value_type = typename std::make_unsigned<T>::type;
+#endif  // defined(MOZ_ZUCCHINI)
   std::vector<uint8_t> buffer;
 
   std::vector<T> values;
@@ -59,11 +64,20 @@ void TestEncodeDecodeVarInt(const std::vector<T>& data) {
     // test cases may result in overflow when computing |value|, but we don't
     // care about that.
     for (int delta = -4; delta <= 4; ++delta) {
+#if !defined(MOZ_ZUCCHINI)
       T value = delta + basis;
+#else
+      T value = unsigned_value_type(delta) + unsigned_value_type(basis);
+#endif  // !defined(MOZ_ZUCCHINI)
       EncodeVarInt(value, std::back_inserter(buffer));
       values.push_back(value);
 
+#if !defined(MOZ_ZUCCHINI)
       value = delta - basis;
+#else
+      value = unsigned_value_type(delta) + unsigned_value_type(-basis);
+#endif  // !defined(MOZ_ZUCCHINI)
+
       EncodeVarInt(value, std::back_inserter(buffer));
       values.push_back(value);
     }
-- 
2.42.0.windows.2