[Android] Short-circuit touch forwarding when no touch handlers exist

content/browser/android/content_view_core_impl.cc

 // Copyright 2012 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 "content/browser/android/content_view_core_impl.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
@@ skipping 1010 matching lines @@
   if (!rwhv)
     return;
 
   const ui::MotionEvent* current_down_event =
       gesture_provider_.GetCurrentDownEvent();
   if (!current_down_event)
     return;
 
   scoped_ptr<ui::MotionEvent> cancel_event = current_down_event->Cancel();
   DCHECK(cancel_event);
-  if (!gesture_provider_.OnTouchEvent(*cancel_event))
-    return;
-
-  rwhv->SendTouchEvent(
-      CreateWebTouchEventFromMotionEvent(*cancel_event, 1.f / dpi_scale()));
+  OnMotionEvent(*cancel_event);
 }
 
 jboolean ContentViewCoreImpl::OnTouchEvent(JNIEnv* env,
                                            jobject obj,
                                            jobject motion_event,
                                            jlong time_ms,
                                            jint android_action,
                                            jint pointer_count,
                                            jint history_size,
                                            jint action_index,
                                            jfloat pos_x_0,
                                            jfloat pos_y_0,
                                            jfloat pos_x_1,
                                            jfloat pos_y_1,
                                            jint pointer_id_0,
                                            jint pointer_id_1,
                                            jfloat touch_major_0,
                                            jfloat touch_major_1) {
   RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
+  // Avoid synthesizing a touch event if it cannot be forwarded.
   if (!rwhv)
     return false;
 
   MotionEventAndroid event(env,
                            motion_event,
                            time_ms,
                            android_action,
                            pointer_count,
                            history_size,
                            action_index,
                            pos_x_0,
                            pos_y_0,
                            pos_x_1,
                            pos_y_1,
                            pointer_id_0,
                            pointer_id_1,
                            touch_major_0,
                            touch_major_1);
 
-  if (!gesture_provider_.OnTouchEvent(event))
-    return false;
-
-  rwhv->SendTouchEvent(WebTouchEventBuilder::Build(event, 1.f / dpi_scale()));
-  return true;
+  return OnMotionEvent(event);
 }
 
 float ContentViewCoreImpl::GetDpiScale() const {
   return dpi_scale_;
 }
 
 jboolean ContentViewCoreImpl::SendMouseMoveEvent(JNIEnv* env,
                                                  jobject obj,
                                                  jlong time_ms,
                                                  jfloat x,
@@ skipping 35 matching lines @@
   rwhv->SendMouseWheelEvent(event);
   return true;
 }
 
 WebGestureEvent ContentViewCoreImpl::MakeGestureEvent(
     WebInputEvent::Type type, int64 time_ms, float x, float y) const {
   return WebGestureEventBuilder::Build(
       type, time_ms / 1000.0, x / dpi_scale(), y / dpi_scale());
 }
 
+bool ContentViewCoreImpl::OnMotionEvent(const ui::MotionEvent& event) {
+  RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
+  if (!rwhv)
+    return false;
+
+  if (!gesture_provider_.OnTouchEvent(event))
+    return false;
+
+  RenderWidgetHostImpl* host = RenderWidgetHostImpl::From(
+      rwhv->GetRenderWidgetHost());
+  if (!host->ShouldForwardTouchEvent()) {
+    ConfirmTouchEvent(INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS);
+    return true;
+  }
+
+  rwhv->SendTouchEvent(
+      CreateWebTouchEventFromMotionEvent(event, 1.f / dpi_scale()));
+  return true;
+}
+
 void ContentViewCoreImpl::SendGestureEvent(
     const blink::WebGestureEvent& event) {
   RenderWidgetHostViewAndroid* rwhv = GetRenderWidgetHostViewAndroid();
   if (rwhv)
     rwhv->SendGestureEvent(event);
 }
 
 void ContentViewCoreImpl::ScrollBegin(JNIEnv* env,
                                       jobject obj,
                                       jlong time_ms,
@@ skipping 638 matching lines @@
       reinterpret_cast<ui::ViewAndroid*>(view_android),
       reinterpret_cast<ui::WindowAndroid*>(window_android));
   return reinterpret_cast<intptr_t>(view);
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content