SF: fix a crash in FlagManager

When dumping the flag, don't dump the server flags if boot
is still in progress.

Test: adb shell dumpsys SurfaceFlinger while booting
Bug: 309017367
Change-Id: I44d12351c55366ff8dae6decb15beebd87db99e1
diff --git a/services/surfaceflinger/FlagManager.h b/services/surfaceflinger/FlagManager.h
index 10784a7..cefce9b 100644
--- a/services/surfaceflinger/FlagManager.h
+++ b/services/surfaceflinger/FlagManager.h
@@ -46,6 +46,10 @@
     bool use_adpf_cpu_hint() const;
     bool use_skia_tracing() const;
 
+    /// Trunk stable server flags ///
+    bool late_boot_misc2() const;
+    bool dont_skip_on_early() const;
+
     /// Trunk stable readonly flags ///
     bool connected_display() const;
     bool enable_small_area_detection() const;
@@ -55,10 +59,6 @@
     bool hdcp_level_hal() const;
     bool multithreaded_present() const;
 
-    /// Trunk stable server flags ///
-    bool late_boot_misc2() const;
-    bool dont_skip_on_early() const;
-
 protected:
     // overridden for unit tests
     virtual std::optional<bool> getBoolProperty(const char*) const;
@@ -69,6 +69,9 @@
 
     FlagManager(const FlagManager&) = delete;
 
+    void dumpFlag(std::string& result, bool readonly, const char* name,
+                  std::function<bool()> getter) const;
+
     std::atomic_bool mBootCompleted = false;
     std::atomic_bool mUnitTestMode = false;