Reland "Reland "Remove references to MessagePump::Type""

This reverts commit 8f5f3e89a5cdc3e67ea177eafa516f768d1f3e92.

Reason for revert: Revert wasn't needed

Original change's description:
> Revert "Reland "Remove references to MessagePump::Type""
> 
> This reverts commit 1c1d61e5d92c70e423c4ea3a378523dd19a05e8f.
> 
> Reason for revert: I suspect this is causing a compile failure on the Linux ChromiumOS Full Bot.
> 
> Output:
> FAILED: obj/chromeos/services/assistant/tests/service_unittest.o
> /b/s/w/ir/cache/goma/client/gomacc ../../third_par...
> ../../chromeos/services/assistant/service_unittest.cc:12:10: fatal error: 'ash/public/interfaces/constants.mojom-forward.h' file not found
> #include "ash/public/interfaces/constants.mojom-forward.h"
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> 
> Original change's description:
> > Reland "Remove references to MessagePump::Type"
> > 
> > This is a reland of bfca9d675c524843b8bb6a0d014e29d4d6859056
> > 
> > Was reverted because an optional trybot failed due to a missing include in an unrelated file.
> > That was fixed in https://crrev.com/c/1729634 and https://crrev.com/c/1730894
> > 
> > Original change's description:
> > > Remove references to MessagePump::Type
> > >
> > > It is going away soon, replace with the real thing: MessagePumpType
> > >
> > > Had to fix a lot of includes (MessagePumpType is defined in message_pump_type.h).
> > >
> > > This is a mechanical change that will be reviewed according to
> > > https://chromium.googlesource.com/chromium/src/+/master/docs/code_reviews.md#mechanical-changes
> > >
> > > Bug: 891670
> > > [email protected]
> > >
> > > Change-Id: I1c85fce3cc11f7a283153ccaf2596e6e92a638d7
> > > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1726058
> > > Commit-Queue: Carlos Caballero <[email protected]>
> > > Reviewed-by: Gabriel Charette <[email protected]>
> > > Cr-Commit-Position: refs/heads/master@{#682731}
> > 
> > [email protected]
> > 
> > Bug: 891670
> > Change-Id: I7654fb4ff3a5e8c0505aafb33939d2035f28f88b
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1730416
> > Commit-Queue: Carlos Caballero <[email protected]>
> > Reviewed-by: Gabriel Charette <[email protected]>
> > Cr-Commit-Position: refs/heads/master@{#683592}
> 
> [email protected],[email protected]
> 
> Change-Id: Ie479741cf8092d9110a9ee6c5fa81e7e084c6788
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: 891670
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1733432
> Reviewed-by: Chris Sharp <[email protected]>
> Commit-Queue: Chris Sharp <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#683602}

[email protected],[email protected],[email protected]

Change-Id: Ieb323e7afaf248384c05b8cb0c13d6ec50856c75
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 891670
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1733434
Reviewed-by: Chris Sharp <[email protected]>
Commit-Queue: Chris Sharp <[email protected]>
Cr-Commit-Position: refs/heads/master@{#683603}
diff --git a/base/task/single_thread_task_executor.cc b/base/task/single_thread_task_executor.cc
index 2c52470..7e12b78 100644
--- a/base/task/single_thread_task_executor.cc
+++ b/base/task/single_thread_task_executor.cc
@@ -4,14 +4,13 @@
 
 #include "base/task/single_thread_task_executor.h"
 
-#include "base/message_loop/message_pump.h"
 #include "base/task/sequence_manager/sequence_manager.h"
 #include "base/task/sequence_manager/sequence_manager_impl.h"
 #include "build/build_config.h"
 
 namespace base {
 
-SingleThreadTaskExecutor::SingleThreadTaskExecutor(MessagePump::Type type)
+SingleThreadTaskExecutor::SingleThreadTaskExecutor(MessagePumpType type)
     : sequence_manager_(sequence_manager::CreateUnboundSequenceManager(
           sequence_manager::SequenceManager::Settings::Builder()
               .SetMessagePumpType(type)
@@ -23,7 +22,7 @@
   sequence_manager_->BindToMessagePump(MessagePump::Create(type));
 
 #if defined(OS_IOS)
-  if (type == MessagePump::Type::UI) {
+  if (type == MessagePumpType::UI) {
     static_cast<sequence_manager::internal::SequenceManagerImpl*>(
         sequence_manager_.get())
         ->AttachToMessagePump();