Implement Cpu Freq Section

When poll from sysfs, revents return POLLERR by default, handles
this edge case in this cl.

Bug: 68774444
Test: unit tested + on device tests
Change-Id: I23540299c026d3e7676497f56690e9f8646a47bd
diff --git a/Android.bp b/Android.bp
index 2c4963c..0d3a0ec 100644
--- a/Android.bp
+++ b/Android.bp
@@ -58,6 +58,7 @@
             // runtime, as well as the only protos that are actually
             // needed by the device.
             srcs: [
+                "core/proto/android/os/cpufreq.proto",
                 "core/proto/android/os/cpuinfo.proto",
                 "core/proto/android/os/kernelwake.proto",
                 "core/proto/android/os/pagetypeinfo.proto",
@@ -82,6 +83,7 @@
     ],
 
     srcs: [
+        "core/proto/android/os/cpufreq.proto",
         "core/proto/android/os/cpuinfo.proto",
         "core/proto/android/os/kernelwake.proto",
         "core/proto/android/os/pagetypeinfo.proto",