AW: add test for multiple FlagOverrideHelpers

No change to logic, only tests. There is a new use case in
https://crrev.com/c/5833784 which involves
multiple FlagOverrideHelper instances. This class wasn't really designed
for this, but it technically does work. This adds test coverage to
explicitly cover this use case and prevent regressions.

Bug: 380498990
Test: out/Default/bin/run_android_webview_junit_tests -f *FlagOverrideHelperTest#*
Change-Id: Ia2e122e1e927b6e2a2e27254469e3d8d276364dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6044551
Auto-Submit: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Adam Walls <avvall@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1387174}

android_webview/junit/src/org/chromium/android_webview/robolectric/common/FlagOverrideHelperTest.java

@@ -282,4 +282,50 @@ public class FlagOverrideHelperTest {
         assertEnabledFeatures(arrayToSet("feature-1"));
         assertDisabledFeatures(arrayToSet("feature-2"));
     }
+
+    @Test
+    @SmallTest
+    public void testMultipleOverrides() {
+        Map<String, Boolean> map1 = new HashMap<>();
+        map1.put("flag-1", true);
+        map1.put("flag-2", false);
+        map1.put("feature-1", true);
+        map1.put("feature-2", false);
+        FlagOverrideHelper helper1 = new FlagOverrideHelper(sMockFlagList);
+        helper1.applyFlagOverrides(map1);
+
+        Assert.assertTrue(
+                "The 'flag-1' commandline flag should be applied",
+                CommandLine.getInstance().hasSwitch("flag-1"));
+        Assert.assertFalse(
+                "The 'flag-2' commandline flag should not be applied",
+                CommandLine.getInstance().hasSwitch("flag-2"));
+        Assert.assertFalse(
+                "The 'flag-3' commandline flag should be off by default",
+                CommandLine.getInstance().hasSwitch("flag-3"));
+        assertEnabledFeatures(arrayToSet("feature-1"));
+        assertDisabledFeatures(arrayToSet("feature-2"));
+
+        Map<String, Boolean> map2 = new HashMap<>();
+        // Try a variety of ways to override.
+        map2.put("flag-1", !map1.get("flag-1")); // invert the switch value
+        map2.put("flag-2", map1.get("flag-2")); // keep the same switch value
+        // Don't do anything with feature-1
+        map2.put("feature-2", !map1.get("feature-2")); // invert the feature value
+        map2.put("flag-3", true); // add a new flag
+        FlagOverrideHelper helper2 = new FlagOverrideHelper(sMockFlagList);
+        helper2.applyFlagOverrides(map2);
+
+        Assert.assertFalse(
+                "The 'flag-1' commandline flag should be removed by the second FlagOverrideHelper",
+                CommandLine.getInstance().hasSwitch("flag-1"));
+        Assert.assertFalse(
+                "The 'flag-2' commandline flag should not be applied by the second"
+                        + " FlagOverrideHelper",
+                CommandLine.getInstance().hasSwitch("flag-2"));
+        Assert.assertTrue(
+                "The 'flag-3' commandline flag should be added by the second FlagOverrideHelper",
+                CommandLine.getInstance().hasSwitch("flag-3"));
+        assertEnabledFeatures(arrayToSet("feature-1", "feature-2"));
+    }
 }