Revert "Enable -Wunreachable-code on Android."

This reverts commit 4a511800.

Reason for revert: break compile on many Android bots. See crbug.com/1064847.

Original change's description:
> Enable -Wunreachable-code on Android.
> 
> Bug: 346399
> Change-Id: I41c8cf8581bff1256a28a15c80bdd59a599b0cc2
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2119759
> Auto-Submit: Nico Weber <thakis@chromium.org>
> Reviewed-by: Bo <boliu@chromium.org>
> Commit-Queue: Bo <boliu@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#753406}

TBR=thakis@chromium.org,boliu@chromium.org

Change-Id: I8cc1fea613255b63987bc1b1cc1c0af1972cf4b7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 346399
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2121468Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753506}

android_webview/test/embedded_test_server/aw_embedded_test_server.cc

@@ -156,16 +156,11 @@ std::unique_ptr<HttpResponse> HandleSetImageResponse(
 
   bool header_exist = false;
   if (query.find("header") != query.end()) {
-    // TODO(thakis): It looks like the break in the loop should be in the if.
-    // Check and fix.
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wunreachable-code"
     for (const auto& header : query.at("header")) {
       if (request.headers.find(header) != request.headers.end())
         header_exist = true;
       break;
     }
-#pragma GCC diagnostic pop
   }
 
   std::string decoded_resource;

build/config/compiler/BUILD.gn

@@ -1591,9 +1591,10 @@ config("chromium_code") {
 
     # TODO(thakis): Enable this more often, https://crbug.com/346399
     # use_libfuzzer: https://crbug.com/1063180
+    # cros/arm has warnings in nacl code.
     if (!is_nacl && !use_libfuzzer &&
-        (target_os == "android" || target_os == "chromeos" ||
-         target_os == "fuchsia" || target_os == "linux")) {
+        (target_os == "chromeos" || target_os == "fuchsia" ||
+         target_os == "linux")) {
       cflags += [ "-Wunreachable-code" ]
     }
 

third_party/blink/renderer/core/html/canvas/image_data.cc

@@ -781,16 +781,13 @@ bool ImageData::ImageDataInCanvasColorSettings(
     src_pixel_format = skcms_PixelFormat_RGBA_ffff;
 
   skcms_PixelFormat dst_pixel_format = skcms_PixelFormat_RGBA_8888;
-  if (canvas_pixel_format == CanvasPixelFormat::kF16) {
-    dst_pixel_format = skcms_PixelFormat_RGBA_hhhh;
-  }
-#if SK_PMCOLOR_BYTE_ORDER(B, G, R, A)
-  else if (canvas_pixel_format ==
-               CanvasColorParams::GetNativeCanvasPixelFormat() &&
-           u8_color_type == kN32ColorType) {
+  if (canvas_pixel_format == CanvasColorParams::GetNativeCanvasPixelFormat() &&
+      u8_color_type == kN32ColorType &&
+      kN32_SkColorType == kBGRA_8888_SkColorType) {
     dst_pixel_format = skcms_PixelFormat_BGRA_8888;
+  } else if (canvas_pixel_format == CanvasPixelFormat::kF16) {
+    dst_pixel_format = skcms_PixelFormat_RGBA_hhhh;
   }
-#endif
 
   skcms_AlphaFormat src_alpha_format = skcms_AlphaFormat_Unpremul;
   skcms_AlphaFormat dst_alpha_format = skcms_AlphaFormat_Unpremul;

third_party/blink/renderer/platform/graphics/gpu/webgl_image_conversion.cc

@@ -2858,11 +2858,7 @@ void WebGLImageConversion::ImageExtractor::ExtractImage(
   if (!skia_image)
     return;
 
-#if SK_B32_SHIFT
-  image_source_format_ = kDataFormatRGBA8;
-#else
-  image_source_format_ = kDataFormatBGRA8;
-#endif
+  image_source_format_ = SK_B32_SHIFT ? kDataFormatRGBA8 : kDataFormatBGRA8;
   image_source_unpack_alignment_ =
       0;  // FIXME: this seems to always be zero - why use at all?