[webengine] Forward --force-protected-video-output-buffers to Renderer

crrev.com/c/4116013 moved handling of the flag to the Renderer, but
the flag is not forwarded to the renderer.

Bug: 1401245, b/266011868
Change-Id: I92878627f5fd10bdd9f00ce6a5a547c6849092ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4205855
Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
Commit-Queue: David Song <wintermelons@google.com>
Cr-Commit-Position: refs/heads/main@{#1098996}

fuchsia_web/webengine/browser/web_engine_content_browser_client.cc

@@ -91,6 +91,7 @@ static constexpr char const* kRendererSwitchesToCopy[] = {
     switches::kCorsExemptHeaders,
     switches::kEnableCastStreamingReceiver,
     switches::kEnableProtectedVideoBuffers,
+    switches::kForceProtectedVideoOutputBuffers,
     switches::kUseOverlaysForVideo,
     switches::kMinVideoDecoderOutputBufferSize,