Move BrowserThread to content namespace.

tools/valgrind/tsan/suppressions.txt

 # There are a few kinds of suppressions in this file.
 # 1. third party stuff we have no control over
 #
 # 2. intentional unit test errors, or stuff that is somehow a false positive
 # in our own code, or stuff that is so trivial it's not worth fixing
 #
 # 3. Suppressions for real chromium bugs that are not yet fixed.
 # These should all be in chromium's bug tracking system (but a few aren't yet).
 # Periodically we should sweep this file and the bug tracker clean by
 # running overnight and removing outdated bugs/suppressions.
@@ skipping 484 matching lines @@
   fun:base::MessagePumpLibevent::FileDescriptorWatcher::~FileDescriptorWatcher
   fun:ProcessSingleton::LinuxWatcher::SocketReader::~SocketReader
   fun:ProcessSingleton::LinuxWatcher::RemoveSocketReader
   fun:ProcessSingleton::LinuxWatcher::SocketReader::FinishWithACK
   fun:ProcessSingleton::LinuxWatcher::HandleMessage
 }
 {
   bug_89141
   ThreadSanitizer:Race
   fun:base::Thread::message_loop
-  fun:BrowserThread::IsMessageLoopValid
+  fun:content::BrowserThread::IsMessageLoopValid
   fun:ThreadWatcherList::StartWatching
   fun:ThreadWatcherList::InitializeAndStartWatching
 }
 {
   bug_93757_a
   ThreadSanitizer:Race
   fun:__memset_sse2
   fun:VisitedLinkMaster::CreateURLTable
 }
 {
@@ skipping 119 matching lines @@
 }
 {
   bug_102134a
   ThreadSanitizer:Race
   fun:content::BrowserThreadImpl::~BrowserThreadImpl
   fun:content::TestBrowserThread::~TestBrowserThread
 }
 {
   bug_102134b
   ThreadSanitizer:Race
-  fun:BrowserThread::~BrowserThread
-  fun:DeprecatedBrowserThread::~DeprecatedBrowserThread
+  fun:content::BrowserThread::~BrowserThread
+  fun:content::DeprecatedBrowserThread::~DeprecatedBrowserThread
 }
 {
   bug_102327_a
   ThreadSanitizer:Race
   fun:tracked_objects::ThreadData::Initialize
   fun:tracked_objects::ThreadData::InitializeThreadContext
   fun:base::Thread::ThreadMain
   fun:base::::ThreadFunc
 }
 {
   bug_102327_b
   ThreadSanitizer:Race
   ...
   fun:tracked_objects::ThreadData::TallyABirthIfActive
   fun:base::PosixDynamicThreadPool::PendingTask::PendingTask
   fun:base::PosixDynamicThreadPool::WaitForTask
   fun:base::::WorkerThread::ThreadMain
   fun:base::::ThreadFunc
 }