gn/linux: warnings as errors, turn on Wextra

Also remove a few redundant consts that result in warnings like:

../../content/common/cursors/webcursor_aurax11.cc:20:1: error: 'const' type qualifier on return type has no effect [-Werror,-Wignored-qualifiers]
const ui::PlatformCursor WebCursor::GetPlatformCursor() {
^~~~~~

TBR=davemoore@chromium.org,sadrul@chromium.org
R=brettw@chromium.org, thakis@chromium.org,rch@chromium.org
BUG=393046, 335824

Review URL: https://codereview.chromium.org/538333002

Cr-Commit-Position: refs/heads/master@{#293930}

12 files changed, 24 insertions, 25 deletions

diff --git a/ash/shelf/shelf_view.h b/ash/shelf/shelf_view.h
index b37cc3e..4a5868c 100644
--- a/ash/shelf/shelf_view.h
+++ b/ash/shelf/shelf_view.h
@@ -133,7 +133,7 @@ class ASH_EXPORT ShelfView : public views::View,
   virtual void EndDrag(bool cancel) OVERRIDE;
 
   // Return the view model for test purposes.
-  const views::ViewModel* const view_model_for_test() const {
+  const views::ViewModel* view_model_for_test() const {
     return view_model_.get();
   }
 
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 59c4673..793ee6a 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -477,8 +477,6 @@ config("runtime_library") {
 # Toggles between higher and lower warnings for code that is (or isn't)
 # part of Chromium.
 
-# TODO: -Werror should always be on, independent of chromium_code
-# http://crbug.com/393046
 config("chromium_code") {
   if (is_win) {
     cflags = [
@@ -487,6 +485,7 @@ config("chromium_code") {
   } else {
     cflags = [
       "-Wall",
+      "-Wextra",
 
       # GCC turns on -Wsign-compare for C++ under -Wall, but clang doesn't,
       # so we specify it explicitly.
@@ -494,11 +493,6 @@ config("chromium_code") {
       # http://code.google.com/p/chromium/issues/detail?id=90453
       "-Wsign-compare",
     ]
-    if (!is_linux) {
-      # TODO: Add this unconditionally once linux builds without warnings with
-      # clang in the gn build.
-      cflags += [ "-Werror" ]
-    }
 
     # In Chromium code, we define __STDC_foo_MACROS in order to get the
     # C99 macros on Mac and Linux.
@@ -506,12 +500,6 @@ config("chromium_code") {
       "__STDC_CONSTANT_MACROS",
       "__STDC_FORMAT_MACROS",
     ]
-
-    # TODO(brettw) this should also be enabled on Linux but some files
-    # currently fail.
-    if (is_mac) {
-      cflags += [ "-Wextra" ]
-    }
   }
 }
 config("no_chromium_code") {
@@ -664,6 +652,7 @@ config("default_warnings") {
     cflags = [
       # Enables.
       "-Wendif-labels",  # Weird old-style text after an #endif.
+      "-Werror",  # Warnings as errors.
 
       # Disables.
       "-Wno-missing-field-initializers",  # "struct foo f = {0};"
diff --git a/build/secondary/third_party/icu/BUILD.gn b/build/secondary/third_party/icu/BUILD.gn
index 4f7f088..1a21949 100644
--- a/build/secondary/third_party/icu/BUILD.gn
+++ b/build/secondary/third_party/icu/BUILD.gn
@@ -258,13 +258,20 @@ component("icui18n") {
   configs += [ ":icu_code" ]
   direct_dependent_configs = [ ":icu_config" ]
 
+  cflags = []
+  if (is_android || is_linux) {
+    cflags += [
+      # ICU uses its own deprecated functions.
+      "-Wno-deprecated-declarations",
+    ]
+  }
   if (is_clang) {
     # uspoof.h has a U_NAMESPACE_USE macro. That's a bug,
     # the header should use U_NAMESPACE_BEGIN instead.
     # http://bugs.icu-project.org/trac/ticket/9054
     configs -= [ "//build/config/clang:extra_warnings" ]
 
-    cflags = [
+    cflags += [
       "-Wno-header-hygiene",
       # Looks like a real issue, see http://crbug.com/114660
       "-Wno-return-type-c-linkage",
diff --git a/build/secondary/third_party/libsrtp/BUILD.gn b/build/secondary/third_party/libsrtp/BUILD.gn
index 8787beb..cfcae79 100644
--- a/build/secondary/third_party/libsrtp/BUILD.gn
+++ b/build/secondary/third_party/libsrtp/BUILD.gn
@@ -212,6 +212,9 @@ if (use_system_libsrtp) {
       if (is_android) {
         defines = [ "HAVE_SYS_SOCKET_H" ]
       }
+      if (is_clang) {
+        cflags = [ "-Wno-implicit-function-declaration" ]
+      }
     }
 
     executable("srtp_test_cipher_driver") {
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_app_menu_item.h b/chrome/browser/ui/ash/launcher/chrome_launcher_app_menu_item.h
index 0612db3..ee0cf57 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_app_menu_item.h
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_app_menu_item.h
@@ -26,7 +26,7 @@ class ChromeLauncherAppMenuItem {
   const gfx::Image& icon() const { return icon_; }
 
   // Returns true if a separator should be inserted before this item.
-  const bool HasLeadingSeparator() const { return has_leading_separator_; }
+  bool HasLeadingSeparator() const { return has_leading_separator_; }
 
   // Returns true if the item is active.
   virtual bool IsActive() const;
diff --git a/content/common/cursors/webcursor.h b/content/common/cursors/webcursor.h
index 45cf9df..d53fbd0 100644
--- a/content/common/cursors/webcursor.h
+++ b/content/common/cursors/webcursor.h
@@ -104,7 +104,7 @@ class CONTENT_EXPORT WebCursor {
 #endif
 
 #if defined(USE_AURA)
-  const ui::PlatformCursor GetPlatformCursor();
+  ui::PlatformCursor GetPlatformCursor();
 
   // Updates |device_scale_factor_| and |rotation_| based on |display|.
   void SetDisplayInfo(const gfx::Display& display);
diff --git a/content/common/cursors/webcursor_aurawin.cc b/content/common/cursors/webcursor_aurawin.cc
index 5f61ed7..15ae5b4 100644
--- a/content/common/cursors/webcursor_aurawin.cc
+++ b/content/common/cursors/webcursor_aurawin.cc
@@ -11,7 +11,7 @@
 
 namespace content {
 
-const ui::PlatformCursor WebCursor::GetPlatformCursor() {
+ui::PlatformCursor WebCursor::GetPlatformCursor() {
   if (!IsCustom())
     return LoadCursor(NULL, IDC_ARROW);
 
diff --git a/content/common/cursors/webcursor_aurax11.cc b/content/common/cursors/webcursor_aurax11.cc
index 91fc942b..dbd2b21 100644
--- a/content/common/cursors/webcursor_aurax11.cc
+++ b/content/common/cursors/webcursor_aurax11.cc
@@ -17,7 +17,7 @@
 
 namespace content {
 
-const ui::PlatformCursor WebCursor::GetPlatformCursor() {
+ui::PlatformCursor WebCursor::GetPlatformCursor() {
   if (platform_cursor_)
     return platform_cursor_;
 
diff --git a/content/common/cursors/webcursor_ozone.cc b/content/common/cursors/webcursor_ozone.cc
index fe3dbd9..39a356d 100644
--- a/content/common/cursors/webcursor_ozone.cc
+++ b/content/common/cursors/webcursor_ozone.cc
@@ -11,7 +11,7 @@
 
 namespace content {
 
-const ui::PlatformCursor WebCursor::GetPlatformCursor() {
+ui::PlatformCursor WebCursor::GetPlatformCursor() {
   if (platform_cursor_)
     return platform_cursor_;
 
diff --git a/net/tools/quic/quic_in_memory_cache.h b/net/tools/quic/quic_in_memory_cache.h
index be091d5..c4b858a 100644
--- a/net/tools/quic/quic_in_memory_cache.h
+++ b/net/tools/quic/quic_in_memory_cache.h
@@ -44,7 +44,7 @@ class QuicInMemoryCache {
     Response() : response_type_(REGULAR_RESPONSE) {}
     ~Response() {}
 
-    const SpecialResponseType response_type() const { return response_type_; }
+    SpecialResponseType response_type() const { return response_type_; }
     const BalsaHeaders& headers() const { return headers_; }
     const base::StringPiece body() const { return base::StringPiece(body_); }
 
diff --git a/ui/keyboard/keyboard_util.cc b/ui/keyboard/keyboard_util.cc
index 438b99c..188aa73 100644
--- a/ui/keyboard/keyboard_util.cc
+++ b/ui/keyboard/keyboard_util.cc
@@ -285,12 +285,12 @@ bool SendKeyEvent(const std::string type,
   return true;
 }
 
-const void MarkKeyboardLoadStarted() {
+void MarkKeyboardLoadStarted() {
   if (!g_keyboard_load_time_start.Get().ToInternalValue())
     g_keyboard_load_time_start.Get() = base::Time::Now();
 }
 
-const void MarkKeyboardLoadFinished() {
+void MarkKeyboardLoadFinished() {
   // Possible to get a load finished without a start if navigating directly to
   // chrome://keyboard.
   if (!g_keyboard_load_time_start.Get().ToInternalValue())
diff --git a/ui/keyboard/keyboard_util.h b/ui/keyboard/keyboard_util.h
index c2b31b8..59b2b24 100644
--- a/ui/keyboard/keyboard_util.h
+++ b/ui/keyboard/keyboard_util.h
@@ -128,11 +128,11 @@ KEYBOARD_EXPORT bool SendKeyEvent(std::string type,
 // Marks that the keyboard load has started. This is used to measure the time it
 // takes to fully load the keyboard. This should be called before
 // MarkKeyboardLoadFinished.
-KEYBOARD_EXPORT const void MarkKeyboardLoadStarted();
+KEYBOARD_EXPORT void MarkKeyboardLoadStarted();
 
 // Marks that the keyboard load has ended. This finishes measuring that the
 // keyboard is loaded.
-KEYBOARD_EXPORT const void MarkKeyboardLoadFinished();
+KEYBOARD_EXPORT void MarkKeyboardLoadFinished();
 
 // Get the list of keyboard resources. |size| is populated with the number of
 // resources in the returned array.