Revert "Enable -Wunreachable-code on Windows."

This reverts commit e334b16e.

Reason for revert: Breaks win-asan

https://ci.chromium.org/p/chromium/builders/ci/win-asan/11193

../../sandbox/win/src/process_mitigations_dyncode_unittest.cc(414,31): error: code will never be executed [-Werror,-Wunreachable-code]
std::wstring test_command = L"CheckPolicy ";
^~~~~~~~~~~~~~~
../../sandbox/win/src/process_mitigations_dyncode_unittest.cc(490,31): error: code will never be executed [-Werror,-Wunreachable-code]
std::wstring test_command = L"CheckPolicy ";
^~~~~~~~~~~~~~~


Original change's description:
> Enable -Wunreachable-code on Windows.
> 
> TBR=reillyg
> 
> Bug: 346399
> Change-Id: I7f52d34dd3be08485c1aace38f2f61d1d4f14176
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2122428
> Commit-Queue: Nico Weber <thakis@chromium.org>
> Auto-Submit: Nico Weber <thakis@chromium.org>
> Reviewed-by: Robert Sesek <rsesek@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#753741}

TBR=thakis@chromium.org,reillyg@chromium.org,rsesek@chromium.org

Change-Id: I289e69d3147aa774a5637fffa850f55015ea5d67
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 346399
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2122434Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753767}

build/config/compiler/BUILD.gn

@@ -1593,7 +1593,7 @@ config("chromium_code") {
     # use_libfuzzer: https://crbug.com/1063180
     if (!is_nacl && !use_libfuzzer &&
         (target_os == "android" || target_os == "chromeos" ||
-         target_os == "fuchsia" || target_os == "linux" || target_os == "win")) {
+         target_os == "fuchsia" || target_os == "linux")) {
       cflags += [ "-Wunreachable-code" ]
     }
 

chrome/browser/upgrade_detector/upgrade_detector_impl.cc

@@ -453,23 +453,23 @@ void UpgradeDetectorImpl::Init() {
   // Register for experiment notifications.
   variations::VariationsService* variations_service =
       g_browser_process->variations_service();
-  if (variations_service) {
+  if (variations_service)
     variations_service->AddObserver(this);
-  }
-
-  // On Windows, only enable upgrade notifications for Google Chrome builds.
-  // Chromium does not use an auto-updater.
-#if !defined(OS_WIN) || BUILDFLAG(GOOGLE_CHROME_BRANDING)
 
-  // On macOS, only enable upgrade notifications if the updater (Keystone) is
-  // present.
-#if defined(OS_MACOSX)
+#if defined(OS_WIN)
+  // Only enable upgrade notifications for Google Chrome builds. Chromium does
+  // not use an auto-updater.
+  if (!BUILDFLAG(GOOGLE_CHROME_BRANDING))
+    return;
+#elif defined(OS_MACOSX)
+  // Only enable upgrade notifications if the updater (Keystone) is present.
   if (!keystone_glue::KeystoneEnabled())
     return;
-#endif
-
-  // On non-macOS non-Windows, always enable upgrade notifications regardless
-  // of branding.
+#elif defined(OS_POSIX)
+    // Always enable upgrade notifications regardless of branding.
+#else
+#error Unsupported platform
+#endif  // defined(OS_WIN)
 
   // Start checking for outdated builds sometime after startup completes.
   base::PostTask(
@@ -482,7 +482,6 @@ void UpgradeDetectorImpl::Init() {
   auto* const build_state = g_browser_process->GetBuildState();
   build_state->AddObserver(this);
   installed_version_poller_.emplace(build_state);
-#endif
 }
 
 void UpgradeDetectorImpl::Shutdown() {

services/shape_detection/detection_utils_win.cc

@@ -37,17 +37,14 @@ ComPtr<ISoftwareBitmap> CreateWinBitmapFromSkBitmap(
   }
 
   ComPtr<ISoftwareBitmap> win_bitmap;
-#if SK_PMCOLOR_BYTE_ORDER(R, G, B, A)
-  const BitmapPixelFormat pixel_format =
-      ABI::Windows::Graphics::Imaging::BitmapPixelFormat_Rgba8;
-#else
-  const BitmapPixelFormat pixel_format =
-      ABI::Windows::Graphics::Imaging::BitmapPixelFormat_Bgra8;
-#endif
+  const BitmapPixelFormat pixelFormat =
+      (kN32_SkColorType == kRGBA_8888_SkColorType)
+          ? ABI::Windows::Graphics::Imaging::BitmapPixelFormat_Rgba8
+          : ABI::Windows::Graphics::Imaging::BitmapPixelFormat_Bgra8;
   // Create ISoftwareBitmap from SKBitmap that is kN32_SkColorType and copy the
   // IBuffer into it.
   hr = bitmap_factory->CreateCopyFromBuffer(
-      buffer.Get(), pixel_format, bitmap.width(), bitmap.height(), &win_bitmap);
+      buffer.Get(), pixelFormat, bitmap.width(), bitmap.height(), &win_bitmap);
   if (FAILED(hr)) {
     DLOG(ERROR) << "Create ISoftwareBitmap from buffer failed: "
                 << logging::SystemErrorCodeToString(hr);