Add FakeDisplaySnapshot builder and related changes.

ui/display/types/fake_display_controller.h

Index: ui/display/types/fake_display_controller.h
diff --git a/ui/display/types/fake_display_controller.h b/ui/display/types/fake_display_controller.h
index 79284eabfe6c459202c3f08f79430c29c4fd178f..72ece3496477187fa21ed3324d2781edd0ca762a 100644
--- a/ui/display/types/fake_display_controller.h
+++ b/ui/display/types/fake_display_controller.h
@@ -7,12 +7,18 @@
 
 #include <stdint.h>
 
+#include <memory>
+
 #include "ui/display/types/display_types_export.h"
 
 namespace gfx {
 class Size;
 }
 
+namespace ui {
+class DisplaySnapshot;
+}
+
 namespace display {
 
 // Controls the fake display state. Provided by the NativeDisplayDelegate if
@@ -24,6 +30,10 @@ class DISPLAY_TYPES_EXPORT FakeDisplayController {
   // |kInvalidDisplayId| if it fails.
   virtual int64_t AddDisplay(const gfx::Size& display_size) = 0;
 
+  // Adds |display| to the list of displays and returns true if successful. Will
+  // fail if an existing display has the same id as |display|.
+  virtual bool AddDisplay(std::unique_ptr<ui::DisplaySnapshot> display) = 0;
+
   // Removes a fake display with specified id, returns true if successful.
   virtual bool RemoveDisplay(int64_t display_id) = 0;