chrome/android: Consume down events for mouse drag gesture.

ui/android/java/src/org/chromium/ui/base/EventForwarder.java

Index: ui/android/java/src/org/chromium/ui/base/EventForwarder.java
diff --git a/ui/android/java/src/org/chromium/ui/base/EventForwarder.java b/ui/android/java/src/org/chromium/ui/base/EventForwarder.java
index 1ffb77f558b57c928b26bd5c0a8e74d5c03ffcba..e8986350d44b04205d4df7579d3d1b13b244d6c8 100644
--- a/ui/android/java/src/org/chromium/ui/base/EventForwarder.java
+++ b/ui/android/java/src/org/chromium/ui/base/EventForwarder.java
@@ -158,7 +158,10 @@ public class EventForwarder {
             // and ACTION_BUTTON_RELEASE respectively because they provide
             // info about the changed-button.
             if (eventAction == MotionEvent.ACTION_DOWN || eventAction == MotionEvent.ACTION_UP) {
-                return false;
+                // While we use the action buttons for the changed state it is important to still
+                // consume the down/up events to get the complete stream for a drag gesture, which
+                // is provided using ACTION_MOVE touch events.
+                return true;
             }
             sendMouseEvent(event.getEventTime(), eventAction, offsetEvent.getX(),
                     offsetEvent.getY(), event.getPointerId(0), event.getPressure(0),