SF: trace the render rate of an app

Add a trace point for both SF and apps when the render rate
is overridden.

Bug: 347314033
Test: manual
Change-Id: I87dc9b17a4c1f97fa43b025cfa684f43c20c5a25
diff --git a/libs/gui/DisplayEventDispatcher.cpp b/libs/gui/DisplayEventDispatcher.cpp
index f3de96d..c46f9c5 100644
--- a/libs/gui/DisplayEventDispatcher.cpp
+++ b/libs/gui/DisplayEventDispatcher.cpp
@@ -15,6 +15,7 @@
  */
 
 #define LOG_TAG "DisplayEventDispatcher"
+#define ATRACE_TAG ATRACE_TAG_GRAPHICS
 
 #include <cinttypes>
 #include <cstdint>
@@ -23,10 +24,13 @@
 #include <gui/DisplayEventReceiver.h>
 #include <utils/Log.h>
 #include <utils/Looper.h>
-
 #include <utils/Timers.h>
+#include <utils/Trace.h>
+
+#include <com_android_graphics_libgui_flags.h>
 
 namespace android {
+using namespace com::android::graphics::libgui;
 
 // Number of events to read at a time from the DisplayEventDispatcher pipe.
 // The value should be large enough that we can quickly drain the pipe
@@ -171,6 +175,13 @@
                     *outDisplayId = ev.header.displayId;
                     *outCount = ev.vsync.count;
                     *outVsyncEventData = ev.vsync.vsyncData;
+
+                    // Trace the RenderRate for this app
+                    if (ATRACE_ENABLED() && flags::trace_frame_rate_override()) {
+                        const auto frameInterval = ev.vsync.vsyncData.frameInterval;
+                        int fps = frameInterval > 0 ? 1e9f / frameInterval : 0;
+                        ATRACE_INT("RenderRate", fps);
+                    }
                     break;
                 case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
                     if (ev.hotplug.connectionError == 0) {