clang/win: Fix -Wextra warnings in webrtc.

webrtc/modules/desktop_capture/win/screen_capturer_win_magnifier.cc

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 218 matching lines @@
 
 BOOL ScreenCapturerWinMagnifier::OnMagImageScalingCallback(
     HWND hwnd,
     void* srcdata,
     MAGIMAGEHEADER srcheader,
     void* destdata,
     MAGIMAGEHEADER destheader,
     RECT unclipped,
     RECT clipped,
     HRGN dirty) {
-  assert(tls_index_.Value() != TLS_OUT_OF_INDEXES);
+  assert(tls_index_.Value() != static_cast<int32_t>(TLS_OUT_OF_INDEXES));
 
   ScreenCapturerWinMagnifier* owner =
       reinterpret_cast<ScreenCapturerWinMagnifier*>(
           TlsGetValue(tls_index_.Value()));
 
   owner->OnCaptured(srcdata, srcheader);
 
   return TRUE;
 }
 
@@ skipping 112 matching lines @@
         magnifier_window_, MW_FILTERMODE_EXCLUDE, 1, &excluded_window_);
     if (!result) {
       mag_uninitialize_func_();
       LOG_F(LS_WARNING) << "Failed to initialize ScreenCapturerWinMagnifier: "
                         << "error from MagSetWindowFilterList "
                         << GetLastError();
       return false;
     }
   }
 
-  if (tls_index_.Value() == TLS_OUT_OF_INDEXES) {
+  if (tls_index_.Value() == static_cast<int32_t>(TLS_OUT_OF_INDEXES)) {
     // More than one threads may get here at the same time, but only one will
     // write to tls_index_ using CompareExchange.
     DWORD new_tls_index = TlsAlloc();
     if (!tls_index_.CompareExchange(new_tls_index, TLS_OUT_OF_INDEXES))
       TlsFree(new_tls_index);
   }
 
-  assert(tls_index_.Value() != TLS_OUT_OF_INDEXES);
+  assert(tls_index_.Value() != static_cast<int32_t>(TLS_OUT_OF_INDEXES));
   TlsSetValue(tls_index_.Value(), this);
 
   magnifier_initialized_ = true;
   return true;
 }
 
 void ScreenCapturerWinMagnifier::OnCaptured(void* data,
                                             const MAGIMAGEHEADER& header) {
   DesktopFrame* current_frame = queue_.current_frame();
 
@@ skipping 49 matching lines @@
   assert(fallback_capturer_);
   if (!fallback_capturer_started_) {
     fallback_capturer_started_ = true;
 
     fallback_capturer_->Start(callback_);
     fallback_capturer_->SelectScreen(current_screen_id_);
   }
 }
 
 }  // namespace webrtc