Add plumbing for upcoming setFrameRate() api

Add plumbing from the app to surface flinger for the
ANativeWindow_setFrameRate() and ASurfaceTransaction_setFrameRate() api
calls we'll be adding soon.

We don't do anything in surface flinger with this data yet.

Bug: 143912624

Test: Added a new test, SetFrameRateTest.
Change-Id: I1cab87f3ce5afca4591a39d8e7a42cb1e86a368f
diff --git a/libs/gui/BufferQueueConsumer.cpp b/libs/gui/BufferQueueConsumer.cpp
index 6418e8c..9b74fef 100644
--- a/libs/gui/BufferQueueConsumer.cpp
+++ b/libs/gui/BufferQueueConsumer.cpp
@@ -775,6 +775,18 @@
     return NO_ERROR;
 }
 
+status_t BufferQueueConsumer::setFrameRate(float frameRate) {
+    std::lock_guard<std::mutex> lock(mCore->mMutex);
+    mCore->mFrameRate = frameRate;
+    return NO_ERROR;
+}
+
+status_t BufferQueueConsumer::getFrameRate(float* frameRate) const {
+    std::lock_guard<std::mutex> lock(mCore->mMutex);
+    *frameRate = mCore->mFrameRate;
+    return NO_ERROR;
+}
+
 status_t BufferQueueConsumer::dumpState(const String8& prefix, String8* outResult) const {
     struct passwd* pwd = getpwnam("shell");
     uid_t shellUid = pwd ? pwd->pw_uid : 0;