fix: bugprone-narrowing-conversions warnings in NativeImage (#44708)

* fix: bugprone-narrowing-conversions warning in NativeImage::memory_usage_

- fix signed / unsigned math by using base/numerics/safe_conversions

- make memory_usage_ an int64_t so it can safely take the size_t
  returned by computeByteSize()

Warning fixed by this commit:

../../electron/shell/common/api/electron_api_native_image.cc:155:26: warning: narrowing conversion from 'size_t' (aka 'unsigned long') to signed type 'int32_t' (aka 'int') is implementation-defined [bugprone-narrowing-conversions]
  155 |       new_memory_usage = image_skia->bitmap()->computeByteSize();

* fix: bugprone-narrowing-conversions warnings in NativeImage::CreateFromBitmap()

`SkImageInfo::MakeN32()` and `SkBitmap::allocN32Pixels()` both take int
width and height args, but we were feeding them unsigned ints.

../../electron/shell/common/api/electron_api_native_image.cc:508:36: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
  508 |   auto info = SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType);
      |                                    ^
../../electron/shell/common/api/electron_api_native_image.cc:508:43: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
  508 |   auto info = SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType);
      |                                           ^
../../electron/shell/common/api/electron_api_native_image.cc:524:25: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
  524 |   bitmap.allocN32Pixels(width, height, false);
      |                         ^
../../electron/shell/common/api/electron_api_native_image.cc:524:32: warning: narrowing conversion from 'unsigned int' to signed type 'int' is implementation-defined [bugprone-narrowing-conversions]
  524 |   bitmap.allocN32Pixels(width, height, false);
      |                                ^
../../electron/shell/common/api/electron_api_native_image.cc:528:48: warning: narrowing conversion from 'double' to 'float' [bugprone-narrowing-conversions]
  528 |       gfx::ImageSkia::CreateFromBitmap(bitmap, scale_factor);

shell/common/api/electron_api_native_image.cc

@@ -12,6 +12,7 @@
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted_memory.h"
+#include "base/numerics/safe_conversions.h"
 #include "base/strings/pattern.h"
 #include "base/strings/utf_string_conversions.h"
 #include "gin/arguments.h"
@@ -147,13 +148,13 @@ NativeImage::~NativeImage() {
 }
 
 void NativeImage::UpdateExternalAllocatedMemoryUsage() {
-  int32_t new_memory_usage = 0;
+  int64_t new_memory_usage = 0;
 
   if (image_.HasRepresentation(gfx::Image::kImageRepSkia)) {
     auto* const image_skia = image_.ToImageSkia();
-    if (!image_skia->isNull()) {
-      new_memory_usage = image_skia->bitmap()->computeByteSize();
-    }
+    if (!image_skia->isNull())
+      new_memory_usage =
+          base::as_signed(image_skia->bitmap()->computeByteSize());
   }
 
   isolate_->AdjustAmountOfExternalAllocatedMemory(new_memory_usage -
@@ -491,9 +492,8 @@ gin::Handle<NativeImage> NativeImage::CreateFromBitmap(
     return gin::Handle<NativeImage>();
   }
 
-  unsigned int width = 0;
-  unsigned int height = 0;
-  double scale_factor = 1.;
+  int width = 0;
+  int height = 0;
 
   if (!options.Get("width", &width)) {
     thrower.ThrowError("width is required");
@@ -505,6 +505,9 @@ gin::Handle<NativeImage> NativeImage::CreateFromBitmap(
     return gin::Handle<NativeImage>();
   }
 
+  if (width <= 0 || height <= 0)
+    return CreateEmpty(thrower.isolate());
+
   auto info = SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType);
   auto size_bytes = info.computeMinByteSize();
 
@@ -514,16 +517,12 @@ gin::Handle<NativeImage> NativeImage::CreateFromBitmap(
     return gin::Handle<NativeImage>();
   }
 
-  options.Get("scaleFactor", &scale_factor);
-
-  if (width == 0 || height == 0) {
-    return CreateEmpty(thrower.isolate());
-  }
-
   SkBitmap bitmap;
   bitmap.allocN32Pixels(width, height, false);
   bitmap.writePixels({info, buffer_data.data(), bitmap.rowBytes()});
 
+  float scale_factor = 1.0F;
+  options.Get("scaleFactor", &scale_factor);
   gfx::ImageSkia image_skia =
       gfx::ImageSkia::CreateFromBitmap(bitmap, scale_factor);
 

shell/common/api/electron_api_native_image.h

@@ -140,7 +140,7 @@ class NativeImage final : public gin::Wrappable<NativeImage> {
   gfx::Image image_;
 
   raw_ptr<v8::Isolate> isolate_;
-  int32_t memory_usage_ = 0;
+  int64_t memory_usage_ = 0;
 };
 
 }  // namespace electron::api