Add RTC_ prefix to (D)CHECKs and related macros.

We must remove dependency on Chromium, i.e. we can't use Chromium's base/logging.h. That means we need to define these macros in WebRTC also when doing Chromium builds. And this causes redefinition.

Alternative solutions:
* Check if we already have defined e.g. CHECK, and don't define them in that case. This makes us depend on include order in Chromium, which is not acceptable.
* Don't allow using the macros in WebRTC headers. Error prone since if someone adds it there by mistake it may compile fine, but later break if a header in added or order is changed in Chromium. That will be confusing and hard to enforce.
* Ensure that headers that are included by an embedder don't include our macros. This would require some heavy refactoring to be maintainable and enforcable.
* Changes in Chromium for this is obviously not an option.

BUG=chromium:468375
NOTRY=true

Review URL: https://codereview.webrtc.org/1335923002

Cr-Commit-Position: refs/heads/master@{#9964}
diff --git a/webrtc/modules/utility/source/process_thread_impl.cc b/webrtc/modules/utility/source/process_thread_impl.cc
index 51b7494..df56fe3 100644
--- a/webrtc/modules/utility/source/process_thread_impl.cc
+++ b/webrtc/modules/utility/source/process_thread_impl.cc
@@ -48,9 +48,9 @@
       thread_name_(thread_name) {}
 
 ProcessThreadImpl::~ProcessThreadImpl() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(!thread_.get());
-  DCHECK(!stop_);
+  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(!thread_.get());
+  RTC_DCHECK(!stop_);
 
   while (!queue_.empty()) {
     delete queue_.front();
@@ -59,12 +59,12 @@
 }
 
 void ProcessThreadImpl::Start() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(!thread_.get());
+  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(!thread_.get());
   if (thread_.get())
     return;
 
-  DCHECK(!stop_);
+  RTC_DCHECK(!stop_);
 
   {
     // TODO(tommi): Since DeRegisterModule is currently being called from
@@ -78,11 +78,11 @@
 
   thread_ = ThreadWrapper::CreateThread(&ProcessThreadImpl::Run, this,
                                         thread_name_);
-  CHECK(thread_->Start());
+  RTC_CHECK(thread_->Start());
 }
 
 void ProcessThreadImpl::Stop() {
-  DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(thread_checker_.CalledOnValidThread());
   if(!thread_.get())
     return;
 
@@ -93,7 +93,7 @@
 
   wake_up_->Set();
 
-  CHECK(thread_->Stop());
+  RTC_CHECK(thread_->Stop());
   stop_ = false;
 
   // TODO(tommi): Since DeRegisterModule is currently being called from
@@ -130,15 +130,15 @@
 }
 
 void ProcessThreadImpl::RegisterModule(Module* module) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(module);
+  RTC_DCHECK(thread_checker_.CalledOnValidThread());
+  RTC_DCHECK(module);
 
 #if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
   {
     // Catch programmer error.
     rtc::CritScope lock(&lock_);
     for (const ModuleCallback& mc : modules_)
-      DCHECK(mc.module != module);
+      RTC_DCHECK(mc.module != module);
   }
 #endif
 
@@ -162,7 +162,7 @@
 void ProcessThreadImpl::DeRegisterModule(Module* module) {
   // Allowed to be called on any thread.
   // TODO(tommi): Disallow this ^^^
-  DCHECK(module);
+  RTC_DCHECK(module);
 
   {
     rtc::CritScope lock(&lock_);