Call Layer::getLayerDebugInfo from the main thread

Fixes an issue where drawing state could be accessed from a binder
thread. The function also mixed current state with drawing state
incorrectly. The function now only retrieves drawing state.

Bug: 150226608
Test: Steps in bug doesn't repro
Test: atest sffakehwc_test
Merged-In: I5537c53e8214e2785473839d71fd483d1a3219b6
Change-Id: I04daedcb9a890083cc710bab30b295e14b9872ae
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 6166789..1a25b82 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1284,22 +1284,15 @@
     return NO_ERROR;
 }
 
-status_t SurfaceFlinger::getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers) const
+status_t SurfaceFlinger::getLayerDebugInfo(std::vector<LayerDebugInfo>* outLayers)
         NO_THREAD_SAFETY_ANALYSIS {
-    // Try to acquire a lock for 1s, fail gracefully
-    const status_t err = mStateLock.timedLock(s2ns(1));
-    const bool locked = (err == NO_ERROR);
-    if (!locked) {
-        ALOGE("LayerDebugInfo: SurfaceFlinger unresponsive (%s [%d]) - exit", strerror(-err), err);
-        return TIMED_OUT;
-    }
-
     outLayers->clear();
-    mCurrentState.traverseInZOrder([&](Layer* layer) {
-        outLayers->push_back(layer->getLayerDebugInfo());
-    });
+    postMessageSync(new LambdaMessage([&]() { 
+            mDrawingState.traverseInZOrder([&](Layer* layer) {
+            outLayers->push_back(layer->getLayerDebugInfo());
+        });
 
-    mStateLock.unlock();
+    }));
     return NO_ERROR;
 }