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 15 matching lines @@
 
 namespace webrtc {
 
 // kMagnifierWindowClass has to be "Magnifier" according to the Magnification
 // API. The other strings can be anything.
 static LPCTSTR kMagnifierHostClass = L"ScreenCapturerWinMagnifierHost";
 static LPCTSTR kHostWindowName = L"MagnifierHost";
 static LPCTSTR kMagnifierWindowClass = L"Magnifier";
 static LPCTSTR kMagnifierWindowName = L"MagnifierWindow";
 
-Atomic32 ScreenCapturerWinMagnifier::tls_index_(TLS_OUT_OF_INDEXES);
+int32_t kTlsIndexNotSet = 0;  // Should not be a valid pointer.

[Sergey Ulanov, 2015/12/09 22:31:51]

Not sure we can use 0 here. Can TlsAlloc() return 0?

[Nico, 2015/12/10 15:05:46]

Hm, you're right. Reverted this to patch set 1.

[Sergey Ulanov, 2015/12/10 17:29:55]

Sorry for not being clear, what I was suggesting initially is to define
kTlsIndexNotSet = static_cast<int32_t>(TLS_OUT_OF_INDEXES), which is the same as
-1.

+Atomic32 ScreenCapturerWinMagnifier::tls_index_(kTlsIndexNotSet);
 
 ScreenCapturerWinMagnifier::ScreenCapturerWinMagnifier(
     rtc::scoped_ptr<ScreenCapturer> fallback_capturer)
     : fallback_capturer_(fallback_capturer.Pass()),
       fallback_capturer_started_(false),
       callback_(NULL),
       current_screen_id_(kFullDesktopScreenId),
       excluded_window_(NULL),
       set_thread_execution_state_failed_(false),
       desktop_dc_(NULL),
@@ skipping 182 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() != kTlsIndexNotSet);
 
   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() == kTlsIndexNotSet) {
     // 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))
+    if (!tls_index_.CompareExchange(new_tls_index, kTlsIndexNotSet))
       TlsFree(new_tls_index);
   }
 
-  assert(tls_index_.Value() != TLS_OUT_OF_INDEXES);
+  assert(tls_index_.Value() != kTlsIndexNotSet);
   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