SF: Prime shader cache before boot animation

Primes the shader cache before launching boot animation to avoid
janking when we eventually fall into GLES composition.

Bug: 30040263
Change-Id: I76ba66e92c5e6bb05930c325f384f3b774e91101
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index e2bd19f..5a0f706 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -509,6 +509,8 @@
     // set initial conditions (e.g. unblank default device)
     initializeDisplays();
 
+    mRenderEngine->primeCache();
+
     // start boot animation
     startBootAnim();