DocsUI: Disable debug logging by default.

Per the platform team, we shouldn't enable debug logging automatically
in debug builds because it increases log-spam.  Just disable the flag
and enable it manually when needed.

Add some ifs to make sure all our debug logging is properly removed.

BUG=27380154

Change-Id: I8338f226c07affdb65970c7cb14f1e6aae036934
diff --git a/src/com/android/documentsui/SearchViewManager.java b/src/com/android/documentsui/SearchViewManager.java
index 63dc2ee..4d0ba4b 100644
--- a/src/com/android/documentsui/SearchViewManager.java
+++ b/src/com/android/documentsui/SearchViewManager.java
@@ -16,6 +16,8 @@
 
 package com.android.documentsui;
 
+import static com.android.documentsui.Shared.DEBUG;
+
 import android.annotation.Nullable;
 import android.os.Bundle;
 import android.provider.DocumentsContract.Root;
@@ -80,7 +82,7 @@
      */
     void update(RootInfo root) {
         if (mMenu == null) {
-            Log.d(TAG, "update called before Search MenuItem installed.");
+            if (DEBUG) Log.d(TAG, "update called before Search MenuItem installed.");
             return;
         }
 
@@ -108,7 +110,7 @@
 
     void showMenu(boolean visible) {
         if (mMenu == null) {
-            Log.d(TAG, "showMenu called before Search MenuItem installed.");
+            if (DEBUG) Log.d(TAG, "showMenu called before Search MenuItem installed.");
             return;
         }