Add the ability to observe MessagePumpMojo

mojo/common/message_pump_mojo_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/common/message_pump_mojo.h"
 
 #include "base/message_loop/message_loop_test.h"
 #include "base/run_loop.h"
 #include "mojo/common/message_pump_mojo_handler.h"
 #include "mojo/public/cpp/system/core.h"
@@ skipping 29 matching lines @@
   int success_count() { return success_count_; }
   int error_count() { return error_count_; }
 
  private:
   int success_count_;
   int error_count_;
 
   DISALLOW_COPY_AND_ASSIGN(CountingMojoHandler);
 };
 
+class CountingObserver : public MessagePumpMojo::Observer {
+ public:
+  virtual void WillSignalHandler() override {
+    will_signal_handler_count++;
+  }
+  virtual void DidSignalHandler() override {
+    did_signal_handler_count++;
+  }
+
+  int will_signal_handler_count = 0;
+  int did_signal_handler_count = 0;
+};
+
 TEST(MessagePumpMojo, RunUntilIdle) {
   base::MessageLoop message_loop(MessagePumpMojo::Create());
   CountingMojoHandler handler;
   MessagePipe handles;
   MessagePumpMojo::current()->AddHandler(&handler,
                                          handles.handle0.get(),
                                          MOJO_HANDLE_SIGNAL_READABLE,
                                          base::TimeTicks());
   WriteMessageRaw(
       handles.handle1.get(), NULL, 0, NULL, 0, MOJO_WRITE_MESSAGE_FLAG_NONE);
   WriteMessageRaw(
       handles.handle1.get(), NULL, 0, NULL, 0, MOJO_WRITE_MESSAGE_FLAG_NONE);
   base::RunLoop run_loop;
   run_loop.RunUntilIdle();
   EXPECT_EQ(2, handler.success_count());
 }
 
+TEST(MessagePumpMojo, Observer) {
+  base::MessageLoop message_loop(MessagePumpMojo::Create());
+
+  CountingObserver observer;
+  MessagePumpMojo::current()->AddObserver(&observer);
+
+  CountingMojoHandler handler;
+  MessagePipe handles;
+  MessagePumpMojo::current()->AddHandler(&handler,
+                                         handles.handle0.get(),
+                                         MOJO_HANDLE_SIGNAL_READABLE,
+                                         base::TimeTicks());
+  WriteMessageRaw(
+      handles.handle1.get(), NULL, 0, NULL, 0, MOJO_WRITE_MESSAGE_FLAG_NONE);
+  base::RunLoop run_loop;
+  run_loop.RunUntilIdle();
+  EXPECT_EQ(1, handler.success_count());
+  EXPECT_EQ(1, observer.will_signal_handler_count);
+  EXPECT_EQ(1, observer.did_signal_handler_count);
+  MessagePumpMojo::current()->RemoveObserver(&observer);
+
+  WriteMessageRaw(
+      handles.handle1.get(), NULL, 0, NULL, 0, MOJO_WRITE_MESSAGE_FLAG_NONE);
+  base::RunLoop run_loop2;
+  run_loop2.RunUntilIdle();
+  EXPECT_EQ(2, handler.success_count());
+  EXPECT_EQ(1, observer.will_signal_handler_count);
+  EXPECT_EQ(1, observer.did_signal_handler_count);
+}
+
 TEST(MessagePumpMojo, UnregisterAfterDeadline) {
   base::MessageLoop message_loop(MessagePumpMojo::Create());
   CountingMojoHandler handler;
   MessagePipe handles;
   MessagePumpMojo::current()->AddHandler(
       &handler,
       handles.handle0.get(),
       MOJO_HANDLE_SIGNAL_READABLE,
       base::TimeTicks::Now() - base::TimeDelta::FromSeconds(1));
   for (int i = 0; i < 2; ++i) {
     base::RunLoop run_loop;
     run_loop.RunUntilIdle();
   }
   EXPECT_EQ(1, handler.error_count());
 }
 
 }  // namespace test
 }  // namespace common
 }  // namespace mojo