feat: add nv12 osr output format.

docs/api/structures/web-preferences.md

@@ -94,6 +94,7 @@
     The actual output pixel format and color space of the texture should refer to [`OffscreenSharedTexture`](../structures/offscreen-shared-texture.md) object in the `paint` event.
     * `argb` - The requested output texture format is 8-bit unorm RGBA, with SRGB SDR color space.
     * `rgbaf16` - The requested output texture format is 16-bit float RGBA, with scRGB HDR color space.
+    * `nv12` - The requested output texture format is 12bpp with Y plane followed by a 2x2 interleaved UV plane, with REC709 color space.
   * `deviceScaleFactor` number (optional) _Experimental_ - The device scale factor of the offscreen rendering output. If not set, will use primary display's scale factor as default.
 * `contextIsolation` boolean (optional) - Whether to run Electron APIs and
   the specified `preload` script in a separate JavaScript context. Defaults

shell/browser/osr/osr_video_consumer.cc

@@ -24,6 +24,8 @@ media::VideoPixelFormat GetTargetPixelFormatFromOption(
     return media::PIXEL_FORMAT_ARGB;
   } else if (pixel_format_option == "rgbaf16") {
     return media::PIXEL_FORMAT_RGBAF16;
+  }else if (pixel_format_option == "nv12") {
+    return media::PIXEL_FORMAT_NV12;
   }
 
   // Use ARGB as default.