mus: Allow a mus app to manually/explicitly ack an event.

Instead of dispatching an input event to all mus::WindowObservers of a
mus::Window, have an explicit mus::InputEventHandler, which is responsible
for processing events for a Window. The InputEventHandler receives the
target, the event, and the ack callback. If it wants to explicitly ack the
event (possibly asynchronously, e.g. chrome renderer, when it receives the
event in the compositor thread, but wants to process the event in the main
thread before ack'ing), it can take the ack callback, and return true to
notify the client-lib.

BUG=none

Review URL: https://codereview.chromium.org/1492963003

Cr-Commit-Position: refs/heads/master@{#363617}

4 files changed, 92 insertions, 1 deletions

diff --git a/components/mus/public/cpp/tests/BUILD.gn b/components/mus/public/cpp/tests/BUILD.gn
index b9cf72b..a8492a0 100644
--- a/components/mus/public/cpp/tests/BUILD.gn
+++ b/components/mus/public/cpp/tests/BUILD.gn
@@ -53,11 +53,13 @@ test("mojo_view_manager_lib_unittests") {
     "//components/mus/public/cpp",
     "//mojo/application/public/cpp",
     "//mojo/converters/geometry",
+    "//mojo/converters/input_events",
     "//mojo/gles2",
     "//mojo/platform_handle:platform_handle_impl",
     "//mojo/public/cpp/system",
     "//testing/gtest",
     "//third_party/mojo/src/mojo/edk/system",
+    "//ui/events",
     "//ui/gfx:test_support",
     "//ui/gfx/geometry",
     "//ui/mojo/geometry:interfaces",
diff --git a/components/mus/public/cpp/tests/test_window_tree.cc b/components/mus/public/cpp/tests/test_window_tree.cc
index 1d70f32..d1f7945 100644
--- a/components/mus/public/cpp/tests/test_window_tree.cc
+++ b/components/mus/public/cpp/tests/test_window_tree.cc
@@ -4,6 +4,8 @@
 
 #include "components/mus/public/cpp/tests/test_window_tree.h"
 
+#include "testing/gtest/include/gtest/gtest.h"
+
 namespace mus {
 
 TestWindowTree::TestWindowTree() : got_change_(false), change_id_(0) {}
@@ -20,6 +22,10 @@ bool TestWindowTree::GetAndClearChangeId(uint32_t* change_id) {
   return true;
 }
 
+bool TestWindowTree::WasEventAcked(uint32_t event_id) const {
+  return acked_events_.count(event_id);
+}
+
 void TestWindowTree::NewWindow(
     uint32_t change_id,
     uint32_t window_id,
@@ -106,7 +112,10 @@ void TestWindowTree::SetImeVisibility(uint32_t window_id,
                                       bool visible,
                                       mojo::TextInputStatePtr state) {}
 
-void TestWindowTree::OnWindowInputEventAck(uint32_t event_id) {}
+void TestWindowTree::OnWindowInputEventAck(uint32_t event_id) {
+  EXPECT_FALSE(acked_events_.count(event_id));
+  acked_events_.insert(event_id);
+}
 void TestWindowTree::WmResponse(uint32_t change_id, bool response) {}
 
 }  // namespace mus
diff --git a/components/mus/public/cpp/tests/test_window_tree.h b/components/mus/public/cpp/tests/test_window_tree.h
index 8a35699..a61c8c9 100644
--- a/components/mus/public/cpp/tests/test_window_tree.h
+++ b/components/mus/public/cpp/tests/test_window_tree.h
@@ -5,6 +5,8 @@
 #ifndef COMPONENTS_MUS_PUBLIC_CPP_TESTS_TEST_WINDOW_TREE_H_
 #define COMPONENTS_MUS_PUBLIC_CPP_TESTS_TEST_WINDOW_TREE_H_
 
+#include <set>
+
 #include "base/macros.h"
 #include "components/mus/public/interfaces/window_tree.mojom.h"
 
@@ -21,6 +23,8 @@ class TestWindowTree : public mojom::WindowTree {
   // invoked since the last GetAndClearChangeId().
   bool GetAndClearChangeId(uint32_t* change_id);
 
+  bool WasEventAcked(uint32_t event_id) const;
+
  private:
   // mojom::WindowTree:
   void NewWindow(
@@ -78,6 +82,7 @@ class TestWindowTree : public mojom::WindowTree {
 
   bool got_change_;
   uint32_t change_id_;
+  std::set<uint32_t> acked_events_;
 
   DISALLOW_COPY_AND_ASSIGN(TestWindowTree);
 };
diff --git a/components/mus/public/cpp/tests/window_tree_client_impl_unittest.cc b/components/mus/public/cpp/tests/window_tree_client_impl_unittest.cc
index 5c61a40..14542b8 100644
--- a/components/mus/public/cpp/tests/window_tree_client_impl_unittest.cc
+++ b/components/mus/public/cpp/tests/window_tree_client_impl_unittest.cc
@@ -6,6 +6,7 @@
 
 #include "base/logging.h"
 #include "components/mus/common/util.h"
+#include "components/mus/public/cpp/input_event_handler.h"
 #include "components/mus/public/cpp/lib/window_private.h"
 #include "components/mus/public/cpp/property_type_converters.h"
 #include "components/mus/public/cpp/tests/test_window.h"
@@ -15,7 +16,10 @@
 #include "components/mus/public/cpp/window_property.h"
 #include "components/mus/public/cpp/window_tree_delegate.h"
 #include "mojo/converters/geometry/geometry_type_converters.h"
+#include "mojo/converters/input_events/input_events_type_converters.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "ui/events/event.h"
+#include "ui/events/event_utils.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace mus {
@@ -96,6 +100,48 @@ class WindowTreeSetup {
   DISALLOW_COPY_AND_ASSIGN(WindowTreeSetup);
 };
 
+class TestInputEventHandler : public InputEventHandler {
+ public:
+  TestInputEventHandler()
+      : received_event_(false), should_manually_ack_(false) {}
+  ~TestInputEventHandler() override {}
+
+  void set_should_manually_ack() { should_manually_ack_ = true; }
+
+  void AckEvent() {
+    DCHECK(should_manually_ack_);
+    DCHECK(!ack_callback_.is_null());
+    ack_callback_.Run();
+    ack_callback_ = base::Closure();
+  }
+
+  void Reset() {
+    received_event_ = false;
+    ack_callback_ = base::Closure();
+  }
+  bool received_event() const { return received_event_; }
+
+ private:
+  // InputEventHandler:
+  void OnWindowInputEvent(Window* target,
+                          mojom::EventPtr event,
+                          scoped_ptr<base::Closure>* ack_callback) override {
+    EXPECT_FALSE(received_event_)
+        << "Observer was not reset after receiving event.";
+    received_event_ = true;
+    if (should_manually_ack_) {
+      ack_callback_ = *ack_callback->get();
+      ack_callback->reset();
+    }
+  }
+
+  bool received_event_;
+  bool should_manually_ack_;
+  base::Closure ack_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestInputEventHandler);
+};
+
 using WindowTreeClientImplTest = testing::Test;
 
 // Verifies bounds are reverted if the server replied that the change failed.
@@ -276,6 +322,35 @@ TEST_F(WindowTreeClientImplTest, SetVisibleFailedWithPendingChange) {
   EXPECT_EQ(original_visible, root->visible());
 }
 
+TEST_F(WindowTreeClientImplTest, InputEventBasic) {
+  WindowTreeSetup setup;
+  Window* root = setup.window_tree_connection()->GetRoot();
+  ASSERT_TRUE(root);
+
+  TestInputEventHandler event_handler;
+  root->set_input_event_handler(&event_handler);
+
+  scoped_ptr<ui::Event> ui_event(
+      new ui::MouseEvent(ui::ET_MOUSE_MOVED, gfx::Point(), gfx::Point(),
+                         ui::EventTimeForNow(), ui::EF_NONE, 0));
+  mojom::EventPtr mus_event = mojom::Event::From(*ui_event);
+  setup.window_tree_client()->OnWindowInputEvent(1, root->id(),
+                                                 std::move(mus_event));
+  EXPECT_TRUE(event_handler.received_event());
+  EXPECT_TRUE(setup.window_tree()->WasEventAcked(1));
+  event_handler.Reset();
+
+  event_handler.set_should_manually_ack();
+  mus_event = mojom::Event::From(*ui_event);
+  setup.window_tree_client()->OnWindowInputEvent(33, root->id(),
+                                                 std::move(mus_event));
+  EXPECT_TRUE(event_handler.received_event());
+  EXPECT_FALSE(setup.window_tree()->WasEventAcked(33));
+
+  event_handler.AckEvent();
+  EXPECT_TRUE(setup.window_tree()->WasEventAcked(33));
+}
+
 // Verifies focus is reverted if the server replied that the change failed.
 TEST_F(WindowTreeClientImplTest, SetFocusFailed) {
   WindowTreeSetup setup;