Shorten debug annotations for predicted candidates

In order to make the candidate layout close to production, especially on Android, this CL shortens debug annotations for predicted candidates.

Those annotations are displayed only in debug build.  Hence no visible change in production is intended.

BUG=none
TEST=compile

git-svn-id: https://mozc.googlecode.com/svn/trunk@451 a6090854-d499-a067-5803-1114d4e51264
diff --git a/src/mozc_version_template.txt b/src/mozc_version_template.txt
index 36ca1a1..47b246d 100644
--- a/src/mozc_version_template.txt
+++ b/src/mozc_version_template.txt
@@ -1,6 +1,6 @@
 MAJOR=2
 MINOR=16
-BUILD=1990
+BUILD=1991
 REVISION=102
 # NACL_DICTIONARY_VERSION is the target version of the system dictionary to be
 # downloaded by NaCl Mozc.
diff --git a/src/prediction/dictionary_predictor.cc b/src/prediction/dictionary_predictor.cc
index 37948bd..a65f28d 100644
--- a/src/prediction/dictionary_predictor.cc
+++ b/src/prediction/dictionary_predictor.cc
@@ -555,25 +555,29 @@
 
 void DictionaryPredictor::SetDebugDescription(PredictionTypes types,
                                               string *description) {
+  string debug_desc;
   if (types & UNIGRAM) {
-    Util::AppendStringWithDelimiter(" ", "Unigram", description);
+    debug_desc.append(1, 'U');
   }
   if (types & BIGRAM) {
-    Util::AppendStringWithDelimiter(" ", "Bigram", description);
+    debug_desc.append(1, 'B');
   }
   if (types & REALTIME_TOP) {
-    Util::AppendStringWithDelimiter(" ", "Realtime Top", description);
+    debug_desc.append("R1");
   } else if (types & REALTIME) {
-    Util::AppendStringWithDelimiter(" ", "Realtime", description);
+    debug_desc.append(1, 'R');
   }
   if (types & SUFFIX) {
-    Util::AppendStringWithDelimiter(" ", "Suffix", description);
+    debug_desc.append(1, 'S');
   }
   if (types & ENGLISH) {
-    Util::AppendStringWithDelimiter(" ", "English", description);
+    debug_desc.append(1, 'E');
   }
   // Note that description for TYPING_CORRECTION is omitted
   // because it is appended by SetDescription.
+  if (!debug_desc.empty()) {
+    Util::AppendStringWithDelimiter(" ", debug_desc, description);
+  }
 }
 
 // return transition_cost[rid][result.lid] + result.wcost (+ penalties).