Updated permission for layer trace proto file.

The layer trace proto file wasn't getting added to the bugreport because
it was missing the other read permission. Added the other read
permission and removed the user execute since it's not needed.

Test: File is added to bugreport
Change-Id: Iacf5455f0f552d2a866d5695a3182a1abe1371a8
diff --git a/services/surfaceflinger/SurfaceTracing.cpp b/services/surfaceflinger/SurfaceTracing.cpp
index 6fd4e46..eb5c7de 100644
--- a/services/surfaceflinger/SurfaceTracing.cpp
+++ b/services/surfaceflinger/SurfaceTracing.cpp
@@ -188,8 +188,11 @@
         ALOGE("Could not save the proto file! Permission denied");
         mLastErr = PERMISSION_DENIED;
     }
-    if (!android::base::WriteStringToFile(output, kDefaultFileName, S_IRWXU | S_IRGRP, getuid(),
-                                          getgid(), true)) {
+
+    // -rw-r--r--
+    const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
+    if (!android::base::WriteStringToFile(output, kDefaultFileName, mode, getuid(), getgid(),
+                                          true)) {
         ALOGE("Could not save the proto file! There are missing fields");
         mLastErr = PERMISSION_DENIED;
     }