Revert 201955 "Allow multiple base::MessagePumpForUI instances t..."

Revert 201955 "Allow multiple base::MessagePumpForUI instances t..."

Broke browser_tests on XP Tests (dbg)(4):
http://build.chromium.org/p/chromium.win/builders/XP%20Tests%20%28dbg%29%284%29/builds/33253

[844:3260:0523/194017:1212046:FATAL:message_window.cc(28)] Check failed: CalledOnValidThread(). 
Backtrace:
  base::Histogram::GetCountAndBucketData [0x08408FD1+2262176]
  base::Histogram::GetCountAndBucketData [0x0827FBBE+651405]
  base::Histogram::GetCountAndBucketData [0x082E1E60+1053487]
  base::Histogram::GetCountAndBucketData [0x0825CC46+508181]
  base::Histogram::GetCountAndBucketData [0x0825BB66+503861]
  base::Histogram::GetCountAndBucketData [0x0825A534+498179]
  base::Histogram::GetCountAndBucketData [0x08256C16+483557]
  base::Histogram::GetCountAndBucketData [0x08256C82+483665]
  base::Histogram::GetCountAndBucketData [0x08256324+481267]
  base::Histogram::GetCountAndBucketData [0x081F59AF+85630]
  base::Histogram::GetCountAndBucketData [0x081F84AC+96635]
  base::Histogram::GetCountAndBucketData [0x081F5917+85478]
  base::Histogram::GetCountAndBucketData [0x08249FD3+431266]
  base::Histogram::GetCountAndBucketData [0x08249255+427812]
  base::Histogram::GetCountAndBucketData [0x082462CD+415644]
  base::Histogram::GetCountAndBucketData [0x0831D883+1297746]
  base::Histogram::GetCountAndBucketData [0x0831D602+1297105]
  ViewHostMsg_TextInputStateChanged::Read [0x0D3DD6F9+6214944]
  ViewHostMsg_TextInputStateChanged::Read [0x0D3DD584+6214571]
  ViewHostMsg_TextInputStateChanged::Read [0x0D33048E+5505717]
  ViewHostMsg_TextInputStateChanged::Read [0x0D3303FA+5505569]
  ViewHostMsg_TextInputStateChanged::Read [0x0D32DDEA+5495825]
  ViewHostMsg_TextInputStateChanged::Read [0x0D32BAC7+5486830]
  ViewHostMsg_TextInputStateChanged::Read [0x0D3DC9B6+6211549]
  ViewHostMsg_TextInputStateChanged::Read [0x0D367071+5729944]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x03E93429+30896697]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x025BD0DF+4853487]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x02701C3F+6183503]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x026EECCB+6105819]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x026EF6DD+6108397]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x026EFEAF+6110399]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x026F673D+6137165]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x02702637+6186055]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x026F4FA0+6131120]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x0262E070+5316224]
  (No symbol) [0x00632BF5]
  RelaunchChromeBrowserWithNewCommandLineIfNeeded [0x03E2BD73+30473091]
  (No symbol) [0x00632975]
  std::_Init_locks::operator= [0x03F5574F+5791]
  std::_Init_locks::operator= [0x03F5557F+5327]
  RegisterWaitForInputIdle [0x7C817077+73]

> Allow multiple base::MessagePumpForUI instances to be created simultanenously on Windows.
> 
> The current implementation of base::MessagePumpForUI on Windows registers a window class with a predefined name in order to create a message-only window. The window class is unregistered when base::MessagePumpForUI is deleted. This causes issues when two or more instances of base::MessagePumpForUI are created/destroyed simultanenously on different threads. For instance once thread can unregister the window class right before the other thread is trying to create a window using this class.
> 
> The CL addresses this problem by switching MessageWindow to implement a message-only window. It also moves MessageWindow from remoting/host/win to base/win along with the corresponding unit test.
> 
> MessageWindow registers a uniquely named window class per MessageWindow instance making sure that different MessageWindow objects do not share any resources. In the future this can be optimized further by registering a common window class shared by all MessageWindow objects in a thread-safe manner (by using LazyInstance for example).
> 
> BUG=241939
> 
> Review URL: https://chromiumcodereview.appspot.com/15261005

TBR=alexeypa@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=201974

[Dan Beam, 2013-05-24 04:29:17]

Committed patchset #1 manually as r201974.