Windows HDR: Disable HDR mode when no HDR or WCG content is present

This allows us to remove the color conversion render pass, and use
a lower-bit depth format.

Bug: 1037954
Change-Id: I6810b1105d47c3690d371f92700182ef4f13e7a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2060664
Commit-Queue: ccameron <ccameron@chromium.org>
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742357}

ui/display/win/screen_win.cc

@@ -211,6 +211,8 @@ Display CreateDisplayFromDisplayInfo(const DisplayInfo& display_info,
   display.set_display_frequency(display_info.display_frequency());
   if (!Display::HasForceDisplayColorProfile()) {
     if (hdr_enabled) {
+      // This will map to DXGI_COLOR_SPACE_RGB_FULL_G22_NONE_P709 with
+      // DXGI_FORMAT_B8G8R8A8_UNORM.
       gfx::DisplayColorSpaces color_spaces(gfx::ColorSpace::CreateSRGB(),
                                            gfx::BufferFormat::BGRA_8888);
 
@@ -225,10 +227,9 @@ Display CreateDisplayFromDisplayInfo(const DisplayInfo& display_info,
       const auto hdr10 =
           gfx::ColorSpace::CreateHDR10(display_info.sdr_white_level());
 
-      // For the moment, always use HDR color space. Once we raster sRGB content
-      // as sRGB, we can dynamically switch in and out of HDR mode.
+      // Use HDR color spaces only when there is WCG or HDR content on the
+      // screen.
       const gfx::ContentColorUsage content_color_usages[] = {
-          gfx::ContentColorUsage::kSRGB,
           gfx::ContentColorUsage::kWideColorGamut,
           gfx::ContentColorUsage::kHDR,
       };