Update DC hardware overlay caps when a monitor is plugged in or unplugged

According to Intel, the overlay support caps might change after a
monitor connection change. This CL re-queries the overlay caps when this
event is observed.

Refactor UpdateHardwareOverlaySupport().

Bug: 1042989
Change-Id: I84ef4ff3dca098f3778f8188fdd7157349480144
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2019768Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Commit-Queue: Maggie Chen <magchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735262}

ui/gl/direct_composition_surface_win.cc

@@ -103,8 +103,6 @@ void UpdateHardwareOverlaySupport() {
     return;
   }
 
-  bool supports_overlays = false;
-  DXGI_FORMAT overlay_format_used = DXGI_FORMAT_NV12;
   unsigned int i = 0;
   while (true) {
     Microsoft::WRL::ComPtr<IDXGIOutput> output;
@@ -141,17 +139,17 @@ void UpdateHardwareOverlaySupport() {
         // performing an extra scaling Blt before calling the driver. Even when
         // scaled overlays aren't actually supported, presentation using the
         // overlay path should be relatively efficient.
-        overlay_format_used = DXGI_FORMAT_NV12;
-        supports_overlays = true;
+        g_overlay_format_used = DXGI_FORMAT_NV12;
+        g_supports_overlays = true;
       }
     }
-    if (!supports_overlays &&
+    if (!g_supports_overlays &&
         FlagsSupportsOverlays(g_yuy2_overlay_support_flags)) {
       // If NV12 isn't supported, fallback to YUY2 if it's supported.
-      overlay_format_used = DXGI_FORMAT_YUY2;
-      supports_overlays = true;
+      g_overlay_format_used = DXGI_FORMAT_YUY2;
+      g_supports_overlays = true;
     }
-    if (supports_overlays) {
+    if (g_supports_overlays) {
       DXGI_OUTPUT_DESC monitor_desc = {};
       if (SUCCEEDED(output3->GetDesc(&monitor_desc))) {
         g_overlay_monitor_size =
@@ -164,22 +162,19 @@ void UpdateHardwareOverlaySupport() {
     // https://docs.microsoft.com/en-us/windows-hardware/drivers/display/multiplane-overlay-hardware-requirements
     // TODO(sunnyps): If the above is true, then we can only look at first
     // output instead of iterating over all outputs.
-    if (supports_overlays)
+    if (g_supports_overlays)
       break;
   }
 
-  g_supports_overlays = supports_overlays;
-  g_overlay_format_used = overlay_format_used;
-
-  if (supports_overlays != prev_supports_overlays ||
-      overlay_format_used != prev_overlay_format_used) {
+  if (g_supports_overlays != prev_supports_overlays ||
+      g_overlay_format_used != prev_overlay_format_used) {
     // Record the new histograms
-    if (supports_overlays) {
+    if (g_supports_overlays) {
       base::UmaHistogramSparse("GPU.DirectComposition.OverlayFormatUsed3",
-                               overlay_format_used);
+                               g_overlay_format_used);
     }
     UMA_HISTOGRAM_BOOLEAN("GPU.DirectComposition.OverlaysSupported",
-                          supports_overlays);
+                          g_supports_overlays);
   }
 }
 
@@ -762,9 +757,15 @@ void DirectCompositionSurfaceWin::HandleVSyncOnMainThread(
 void DirectCompositionSurfaceWin::OnGpuSwitched(
     gl::GpuPreference active_gpu_heuristic) {}
 
-void DirectCompositionSurfaceWin::OnDisplayAdded() {}
+void DirectCompositionSurfaceWin::OnDisplayAdded() {
+  InvalidateOverlayCaps();
+  UpdateHardwareOverlaySupport();
+}
 
-void DirectCompositionSurfaceWin::OnDisplayRemoved() {}
+void DirectCompositionSurfaceWin::OnDisplayRemoved() {
+  InvalidateOverlayCaps();
+  UpdateHardwareOverlaySupport();
+}
 
 scoped_refptr<base::TaskRunner>
 DirectCompositionSurfaceWin::GetWindowTaskRunnerForTesting() {