diff --git a/chrome/browser/autocomplete/chrome_autocomplete_scheme_classifier.cc b/chrome/browser/autocomplete/chrome_autocomplete_scheme_classifier.cc
index 1f10ace4aade2..25e1e62a877ca 100644
--- a/chrome/browser/autocomplete/chrome_autocomplete_scheme_classifier.cc
+++ b/chrome/browser/autocomplete/chrome_autocomplete_scheme_classifier.cc
@@ -91,7 +91,7 @@ ChromeAutocompleteSchemeClassifier::GetInputTypeForScheme(
       // between URL schemes with handers and those without. This will
       // make the default behaviour be search on Linux.
       return metrics::OmniboxInputType::EMPTY;
-#endif // defined(OS_LINUX)
+#else
       // If block state is unknown, check if there is an application registered
       // for the url scheme.
       GURL url(scheme + "://");
@@ -99,6 +99,7 @@ ChromeAutocompleteSchemeClassifier::GetInputTypeForScheme(
           shell_integration::GetApplicationNameForProtocol(url);
       return application_name.empty() ? metrics::OmniboxInputType::EMPTY
                                       : metrics::OmniboxInputType::URL;
+#endif  // defined(OS_LINUX)
     }
   }
   NOTREACHED();
diff --git a/chrome/browser/first_run/first_run_internal_posix.cc b/chrome/browser/first_run/first_run_internal_posix.cc
index db313b4d05f58..d6f97e19f35c4 100644
--- a/chrome/browser/first_run/first_run_internal_posix.cc
+++ b/chrome/browser/first_run/first_run_internal_posix.cc
@@ -57,8 +57,7 @@ bool ShouldShowFirstRunDialog() {
 #if !BUILDFLAG(GOOGLE_CHROME_BRANDING)
   // On non-official builds, only --force-first-run-dialog will show the dialog.
   return false;
-#endif
-
+#else
   base::FilePath local_state_path;
   base::PathService::Get(chrome::FILE_LOCAL_STATE, &local_state_path);
   if (base::PathExists(local_state_path))
@@ -83,6 +82,7 @@ bool ShouldShowFirstRunDialog() {
       is_opt_in ? metrics::EnableMetricsDefault::OPT_IN
                 : metrics::EnableMetricsDefault::OPT_OUT);
   return true;
+#endif
 }
 #endif  // !OS_CHROMEOS
 
diff --git a/components/optimization_guide/optimization_guide_store_unittest.cc b/components/optimization_guide/optimization_guide_store_unittest.cc
index fc772cc9c9624..8b0de5e78d4af 100644
--- a/components/optimization_guide/optimization_guide_store_unittest.cc
+++ b/components/optimization_guide/optimization_guide_store_unittest.cc
@@ -397,12 +397,10 @@ class OptimizationGuideStoreTest : public testing::Test {
       const auto& hint_entry = db_store_.find(hint_entry_key);
       if (hint_entry == db_store_.end()) {
         FAIL() << "No entry found for component hint: " << hint_entry_key;
-        continue;
       }
 
       if (!hint_entry->second.has_hint()) {
         FAIL() << "Component hint entry does not have hint: " << hint_entry_key;
-        continue;
       }
 
       EXPECT_EQ(hint_entry->second.hint().key(), host_suffix);
@@ -1277,7 +1275,6 @@ TEST_F(OptimizationGuideStoreTest, LoadHintSuccessInitialData) {
     OptimizationGuideStore::EntryKey hint_entry_key;
     if (!guide_store()->FindHintEntryKey(host_suffix, &hint_entry_key)) {
       FAIL() << "Hint entry not found for host suffix: " << host_suffix;
-      continue;
     }
 
     guide_store()->LoadHint(
@@ -1291,7 +1288,6 @@ TEST_F(OptimizationGuideStoreTest, LoadHintSuccessInitialData) {
     EXPECT_EQ(last_loaded_entry_key(), hint_entry_key);
     if (!last_loaded_hint()) {
       FAIL() << "Loaded hint was null for entry key: " << hint_entry_key;
-      continue;
     }
 
     EXPECT_EQ(last_loaded_hint()->hint()->key(), host_suffix);
@@ -1321,7 +1317,6 @@ TEST_F(OptimizationGuideStoreTest, LoadHintSuccessUpdateData) {
     OptimizationGuideStore::EntryKey hint_entry_key;
     if (!guide_store()->FindHintEntryKey(host_suffix, &hint_entry_key)) {
       FAIL() << "Hint entry not found for host suffix: " << host_suffix;
-      continue;
     }
 
     guide_store()->LoadHint(
@@ -1335,7 +1330,6 @@ TEST_F(OptimizationGuideStoreTest, LoadHintSuccessUpdateData) {
     EXPECT_EQ(last_loaded_entry_key(), hint_entry_key);
     if (!last_loaded_hint()) {
       FAIL() << "Loaded hint was null for entry key: " << hint_entry_key;
-      continue;
     }
 
     EXPECT_EQ(last_loaded_hint()->hint()->key(), host_suffix);
@@ -1998,7 +1992,6 @@ TEST_F(OptimizationGuideStoreTest, LoadHostModelFeaturesForHost) {
     if (!last_loaded_host_model_features()) {
       FAIL() << "Loaded host model features was null for entry key: "
              << entry_key;
-      continue;
     }
 
     EXPECT_EQ(last_loaded_host_model_features()->host(), host_suffix);
diff --git a/content/browser/media/key_system_support_impl.cc b/content/browser/media/key_system_support_impl.cc
index 93de83d1162d3..51b7465881807 100644
--- a/content/browser/media/key_system_support_impl.cc
+++ b/content/browser/media/key_system_support_impl.cc
@@ -118,9 +118,7 @@ void GetHardwareSecureDecryptionCaps(
 #if !BUILDFLAG(ENABLE_MOJO_VIDEO_DECODER)
   DVLOG(1) << "Hardware secure codecs not supported because mojo video "
               "decode was disabled at buildtime";
-  return;
-#endif
-
+#else
   base::flat_set<media::VideoCodec> video_codec_set;
   base::flat_set<media::EncryptionScheme> encryption_scheme_set;
 
@@ -130,6 +128,7 @@ void GetHardwareSecureDecryptionCaps(
 
   *video_codecs = SetToVector(video_codec_set);
   *encryption_schemes = SetToVector(encryption_scheme_set);
+#endif
 }
 
 }  // namespace
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index 011975dad935a..3a8dcdc696ece 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -1575,7 +1575,8 @@ void PDFiumEngine::StartFind(const std::string& text, bool case_sensitive) {
     base::string16 str = base::UTF8ToUTF16(text);
     // Don't use PDFium to search for now, since it doesn't support unicode
     // text. Leave the code for now to avoid bit-rot, in case it's fixed later.
-    if (0) {
+    // The extra parens suppress a -Wunreachable-code warning.
+    if ((0)) {
       SearchUsingPDFium(str, case_sensitive, first_search,
                         character_to_start_searching_from, current_page);
     } else {
diff --git a/third_party/blink/renderer/core/frame/local_frame_view.cc b/third_party/blink/renderer/core/frame/local_frame_view.cc
index 99c0af61a253e..0dc52a639d8a7 100644
--- a/third_party/blink/renderer/core/frame/local_frame_view.cc
+++ b/third_party/blink/renderer/core/frame/local_frame_view.cc
@@ -4438,9 +4438,7 @@ void LocalFrameView::UpdateLayerDebugInfoEnabled() {
   DCHECK(frame_->IsLocalRoot());
 #if DCHECK_IS_ON()
   DCHECK(layer_debug_info_enabled_);
-  return;
-#endif
-
+#else
   bool should_enable =
       cc::frame_viewer_instrumentation::IsTracingLayerTreeSnapshots() ||
       WebTestSupport::IsRunningWebTest() ||
@@ -4449,6 +4447,7 @@ void LocalFrameView::UpdateLayerDebugInfoEnabled() {
     layer_debug_info_enabled_ = should_enable;
     SetPaintArtifactCompositorNeedsUpdate();
   }
+#endif
 }
 
 OverlayInterstitialAdDetector&
diff --git a/third_party/blink/renderer/platform/graphics/paint/paint_controller_test.cc b/third_party/blink/renderer/platform/graphics/paint/paint_controller_test.cc
index 44d861e597fd2..cacaa2c7a952d 100644
--- a/third_party/blink/renderer/platform/graphics/paint/paint_controller_test.cc
+++ b/third_party/blink/renderer/platform/graphics/paint/paint_controller_test.cc
@@ -1621,9 +1621,7 @@ TEST_P(PaintControllerTest, DuplicatedSubsequences) {
 #if DCHECK_IS_ON()
   EXPECT_DEATH(paint_duplicated_subsequences(),
                "Multiple subsequences for client: \"test\"");
-  return;
-#endif
-
+#else
   // The following is for non-DCHECK path. No security CHECK should trigger.
   paint_duplicated_subsequences();
   // Paint again.
@@ -1642,6 +1640,7 @@ TEST_P(PaintControllerTest, DuplicatedSubsequences) {
     DrawRect(context, client, kForegroundType, FloatRect(100, 100, 100, 100));
   }
   CommitAndFinishCycle();
+#endif
 }
 
 TEST_P(PaintControllerTest, DeletedClientInUnderInvaldiatedSubsequence) {