Use type inference where possible.

Normalize use of Annotations like VisibleForTesting, Nullable and so on.
Also, fix a small issue where we were not doubling the marging on cells when calculating columns for grid view.

Change-Id: Ia02f683c2682fa8d0963d13f253a359911d27965
diff --git a/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java b/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java
index 878c4c2..4685c41 100644
--- a/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java
+++ b/packages/DocumentsUI/src/com/android/documentsui/QuickViewIntentBuilder.java
@@ -18,7 +18,6 @@
 
 import static com.android.documentsui.model.DocumentInfo.getCursorString;
 
-import android.annotation.Nullable;
 import android.content.ClipData;
 import android.content.ClipDescription;
 import android.content.ComponentName;
@@ -28,6 +27,7 @@
 import android.net.Uri;
 import android.provider.DocumentsContract;
 import android.provider.DocumentsContract.Document;
+import android.support.annotation.Nullable;
 import android.util.Log;
 
 import com.android.documentsui.BaseActivity.DocumentContext;