Remove calls to deprecated MessageLoop methods in tools.

tools/gn/loader_unittest.cc

Index: tools/gn/loader_unittest.cc
diff --git a/tools/gn/loader_unittest.cc b/tools/gn/loader_unittest.cc
index 47d0f80d5f99a30fe3cbdea5c6d82e8fe9769bbf..e8d809d62512026dedbc0f8ed97da0193d4f162c 100644
--- a/tools/gn/loader_unittest.cc
+++ b/tools/gn/loader_unittest.cc
@@ -8,6 +8,7 @@
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/err.h"
@@ -146,12 +147,12 @@ TEST_F(LoaderTest, Foo) {
 
   // Completing the build config load should kick off the root build file load.
   mock_ifm_.IssueAllPending();
-  scheduler_.main_loop()->RunUntilIdle();
+  base::RunLoop().RunUntilIdle();

[Nico, 2016/06/22 18:22:28]

(this replacement looks like it makes things more singleton-y and seems like a
step back to me)

[fdoray, 2016/06/22 18:41:50]

Ironically, a goal of base::RunLoop is to make things less singleton-y.

Currently, the last call to MessageLoop::Run on the thread can be exited by
calling MessageLoop::current()->QuitNow/QuitWhenIdle.

On the other hand, to call RunLoop::Quit/QuitWhenIdle, you need a pointer to a
RunLoop (i.e. you must know which RunLoop you exit and the owned of the RunLoop
must have allowed you to do that).

Using RunLoop makes code more base/task_scheduler friendly (doesn't assume that
it is running on a MessageLoop). Maybe having a base::RunLoop constructor that
takes a MessageLoop as argument (and DCHECK_EQ(base::MessageLoop::current,
message_loop) would make things less singleton-y?

Note that scheduler_.main_loop()->RunUntilIdle(); is extremely misleading! It
runs the current thread's MessageLoop, not necessarily scheduler_.main_loop()
(see
https://cs.chromium.org/chromium/src/base/message_loop/message_loop.cc?sq=pac...)

   EXPECT_TRUE(mock_ifm_.HasOnePending(root_build));
 
   // Load the root build file.
   mock_ifm_.IssueAllPending();
-  scheduler_.main_loop()->RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
 
   // Schedule some other file to load in another toolchain.
   Label second_tc(SourceDir("//tc2/"), "tc2");
@@ -162,7 +163,7 @@ TEST_F(LoaderTest, Foo) {
   // Running the toolchain file should schedule the build config file to load
   // for that toolchain.
   mock_ifm_.IssueAllPending();
-  scheduler_.main_loop()->RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
 
   // We have to tell it we have a toolchain definition now (normally the
   // builder would do this).
@@ -179,7 +180,7 @@ TEST_F(LoaderTest, Foo) {
 
   // Running the build config file should make our third file pending.
   mock_ifm_.IssueAllPending();
-  scheduler_.main_loop()->RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
   EXPECT_TRUE(mock_ifm_.HasTwoPending(second_file, third_file));
 
   EXPECT_FALSE(scheduler_.is_failed());