cros: Make autoclick work under mash

Generate synthetic clicks and dispatch them via the window service.
Add the remote event dispatcher interface to a new "accessibility"
capability, available only to trusted apps.

Bug: 821471, 628665
Test: Use autoclick on multiple displays with different scale factors
Change-Id: I61352a0849a96a2bc0ae14d0b8afcca051ba67e2
Reviewed-on: https://chromium-review.googlesource.com/961668Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543190}

ash/autoclick/common/autoclick_controller_common_delegate.h

@@ -28,7 +28,8 @@ class AutoclickControllerCommonDelegate {
   virtual void UpdateAutoclickRingWidget(views::Widget* widget,
                                          const gfx::Point& point_in_screen) = 0;
 
-  // Generates a click with |mouse_event_flags| at |point_in_screen|.
+  // Generates a click at |point_in_screen|. |mouse_event_flags| may contain key
+  // modifiers (e.g. shift, control) for the click.
   virtual void DoAutoclick(const gfx::Point& point_in_screen,
                            const int mouse_event_flags) = 0;
 

ash/components/autoclick/DEPS

@@ -8,5 +8,7 @@ include_rules = [
   "+services/ui/public",
   "+ui/aura/mus",
   "+ui/base",
+  "+ui/display",
+  "+ui/events",
   "+ui/views",
 ]

ash/components/autoclick/autoclick_application.cc

@@ -7,14 +7,20 @@
 #include <utility>
 
 #include "ash/public/cpp/shell_window_ids.h"
+#include "base/bind_helpers.h"
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "services/service_manager/public/cpp/service_context.h"
 #include "services/ui/public/cpp/property_type_converters.h"
+#include "services/ui/public/interfaces/constants.mojom.h"
+#include "services/ui/public/interfaces/remote_event_dispatcher.mojom.h"
 #include "services/ui/public/interfaces/window_manager_constants.mojom.h"
 #include "ui/aura/mus/property_converter.h"
 #include "ui/base/ui_base_types.h"
+#include "ui/display/display.h"
+#include "ui/display/screen.h"
+#include "ui/events/base_event_utils.h"
 #include "ui/views/mus/aura_init.h"
 #include "ui/views/mus/mus_client.h"
 #include "ui/views/mus/pointer_watcher_event_router.h"
@@ -166,8 +172,36 @@ void AutoclickApplication::UpdateAutoclickRingWidget(
 
 void AutoclickApplication::DoAutoclick(const gfx::Point& point_in_screen,
                                        const int mouse_event_flags) {
-  // TODO(riajiang): Currently not working. Need to know how to generate events
-  // in mus world. https://crbug.com/628665
+  // The window service expects display pixel coordinates for events.
+  display::Display display =
+      display::Screen::GetScreen()->GetDisplayNearestPoint(point_in_screen);
+  gfx::Point point_in_root(point_in_screen);
+  point_in_root -= display.bounds().OffsetFromOrigin();
+  gfx::Point point_in_pixels =
+      gfx::ScaleToFlooredPoint(point_in_root, display.device_scale_factor());
+
+  // Connect to the window service event generation interface.
+  ui::mojom::RemoteEventDispatcherPtr remote_event_dispatcher;
+  context()->connector()->BindInterface(ui::mojom::kServiceName,
+                                        &remote_event_dispatcher);
+
+  // Inject a synthetic click.
+  ui::MouseEvent press_event(ui::ET_MOUSE_PRESSED, point_in_pixels,
+                             point_in_pixels, ui::EventTimeForNow(),
+                             mouse_event_flags | ui::EF_LEFT_MOUSE_BUTTON,
+                             ui::EF_LEFT_MOUSE_BUTTON);
+  ui::MouseEvent release_event(ui::ET_MOUSE_RELEASED, point_in_pixels,
+                               point_in_pixels, ui::EventTimeForNow(),
+                               mouse_event_flags | ui::EF_LEFT_MOUSE_BUTTON,
+                               ui::EF_LEFT_MOUSE_BUTTON);
+  remote_event_dispatcher->DispatchEvent(
+      display.id(), std::make_unique<ui::PointerEvent>(press_event),
+      base::BindOnce([](bool result) { DCHECK(result); }));
+  // Don't check the next dispatch result because it's possible the first event
+  // will initiate shutdown.
+  remote_event_dispatcher->DispatchEvent(
+      display.id(), std::make_unique<ui::PointerEvent>(release_event),
+      base::DoNothing());
 }
 
 void AutoclickApplication::OnAutoclickCanceled() {

ash/components/autoclick/autoclick_application.h

@@ -24,6 +24,9 @@ class Widget;
 
 namespace autoclick {
 
+// AutoclickApplication is a mojo mini-app that implements the accessibility
+// autoclick feature. The feature watches for the mouse to stop moving then
+// generates a click after a short delay.
 class AutoclickApplication : public service_manager::Service,
                              public mash::mojom::Launchable,
                              public mojom::AutoclickController,

ash/components/autoclick/manifest.json

@@ -10,7 +10,8 @@
       },
       "requires": {
         "*": [ "app" ],
-        "service_manager": [ "service_manager:service_manager" ]
+        "service_manager": [ "service_manager:service_manager" ],
+        "ui": [ "privileged" ]
       }
     }
   }

services/ui/manifest.json

@@ -54,6 +54,10 @@
         "input_device_controller": [
           "ui::mojom::InputDeviceController"
         ],
+        "privileged": [
+          // Injecting events is security-sensitive.
+          "ui::mojom::RemoteEventDispatcher"
+        ],
         "window_manager": [
           "discardable_memory::mojom::DiscardableSharedMemoryManager",
           "display::mojom::DisplayController",