Enable Wextra and Wno-unused-parameters in default cflags

R=viettrungluu@chromium.org

Review URL: https://codereview.chromium.org/2088563002 .

build/config/compiler/BUILD.gn

diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 5bbf619..cc2b7ac 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -823,6 +823,8 @@
     # code generated by flex (used in angle) contains that keyword.
     # http://crbug.com/255186
     "-Wno-deprecated-register",
+
+    "-Wno-unused-parameter",
   ]
 
   # NaCl's Clang compiler and Chrome's hermetic Clang compiler will almost
@@ -845,12 +847,7 @@
 config("chromium_code") {
   cflags = [
     "-Wall",
-
-    # GCC turns on -Wsign-compare for C++ under -Wall, but clang doesn't,
-    # so we specify it explicitly.
-    # TODO(fischman): remove this if http://llvm.org/PR10448 obsoletes it.
-    # http://code.google.com/p/chromium/issues/detail?id=90453
-    "-Wsign-compare",
+    "-Wextra",
   ]
 
   # In Chromium code, we define __STDC_foo_MACROS in order to get the

services/prediction/dictionary_service.cc

diff --git a/services/prediction/dictionary_service.cc b/services/prediction/dictionary_service.cc
index e9fbc86..7332b97 100644
--- a/services/prediction/dictionary_service.cc
+++ b/services/prediction/dictionary_service.cc
@@ -44,7 +44,7 @@
   dic_file.close();
 }
 
-latinime::Dictionary* const DictionaryService::OpenDictionary(
+latinime::Dictionary* DictionaryService::OpenDictionary(
     const std::string path,
     const int start_offset,
     const int size,

services/prediction/dictionary_service.h

diff --git a/services/prediction/dictionary_service.h b/services/prediction/dictionary_service.h
index 7af1d56..e171cff 100644
--- a/services/prediction/dictionary_service.h
+++ b/services/prediction/dictionary_service.h
@@ -31,10 +31,10 @@
  private:
   void CreatDictFromEmbeddedDataIfNotExist(const std::string path);
 
-  latinime::Dictionary* const OpenDictionary(const std::string path,
-                                             const int start_offset,
-                                             const int size,
-                                             const bool is_updatable);
+  latinime::Dictionary* OpenDictionary(const std::string path,
+                                       const int start_offset,
+                                       const int size,
+                                       const bool is_updatable);
 
   latinime::PrevWordsInfo ProcessPrevWord(
       mojo::Array<PrevWordInfoPtr>& prev_words);