gpu: Replace GpuMsg_GpuSwitched with mojom api.

services/ui/gpu/interfaces/gpu_service.mojom

Index: services/ui/gpu/interfaces/gpu_service.mojom
diff --git a/services/ui/gpu/interfaces/gpu_service.mojom b/services/ui/gpu/interfaces/gpu_service.mojom
index eb2c89b6cd0922a8e923d9dd5ea691dd7c3b3e85..6226e83210545ad1109a38eb84434dd8d558bfd7 100644
--- a/services/ui/gpu/interfaces/gpu_service.mojom
+++ b/services/ui/gpu/interfaces/gpu_service.mojom
@@ -50,6 +50,10 @@ interface GpuService {
   // Tells GPU to wake up the GPU because we're about to draw.
   WakeUpGpu();
 
+  // Tells GPU that host has seen a GPU switch. This can happen when the display
+  // is reconfigured, for example.
+  GpuSwitched();
+
   DestroyAllChannels();
 
   Crash();