Route OnDragEvent through ViewAndroid tree

ui/events/android/motion_event_android.h

 // Copyright 2014 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.
 
 #ifndef UI_EVENTS_ANDROID_MOTION_EVENT_ANDROID_H_
 #define UI_EVENTS_ANDROID_MOTION_EVENT_ANDROID_H_
 
 #include <jni.h>
 #include <stddef.h>
 #include <stdint.h>
@@ skipping 50 matching lines @@
                      jint action_index,
                      jint android_action_button,
                      jint android_button_state,
                      jint meta_state,
                      jfloat raw_offset_x_pixels,
                      jfloat raw_offset_y_pixels,
                      const Pointer* const pointer0,
                      const Pointer* const pointer1);
   ~MotionEventAndroid() override;
 
-  std::unique_ptr<MotionEventAndroid> Offset(float x, float y) const;
+  // Create a new instance from |this| with its cached pointers set
+  // to a given point.
+  std::unique_ptr<MotionEventAndroid> CreateFor(const gfx::PointF& point) const;
+
+  // Convenience method returning the pointer at index 0.
+  gfx::PointF GetPoint() const { return gfx::PointF(GetX(0), GetY(0)); }
 
   // ui::MotionEvent methods.
   uint32_t GetUniqueEventId() const override;
   Action GetAction() const override;
   int GetActionIndex() const override;
   size_t GetPointerCount() const override;
   int GetPointerId(size_t pointer_index) const override;
   float GetX(size_t pointer_index) const override;
   float GetY(size_t pointer_index) const override;
   float GetRawX(size_t pointer_index) const override;
@@ skipping 24 matching lines @@
   float time_sec() const { return time_sec_; }
   float GetTickMultiplier() const;
 
   base::android::ScopedJavaLocalRef<jobject> GetJavaObject() const;
 
  private:
   struct CachedPointer;
 
   float ToDips(float pixels) const;
   CachedPointer FromAndroidPointer(const Pointer& pointer) const;
-  CachedPointer OffsetCachedPointer(const CachedPointer& pointer,
-                                    float x,
-                                    float y) const;
+  CachedPointer CreateCachedPointer(const CachedPointer& pointer,
+                                    const gfx::PointF& point) const;
 
   // Cache pointer coords, id's and major lengths for the most common
   // touch-related scenarios, i.e., scrolling and pinching.  This prevents
   // redundant JNI fetches for the same bits.
   enum { MAX_POINTERS_TO_CACHE = 2 };
 
   // The Java reference to the underlying MotionEvent.
   base::android::ScopedJavaGlobalRef<jobject> event_;
 
   // Used to convert pixel coordinates from the Java-backed MotionEvent to
@@ skipping 31 matching lines @@
   const uint32_t unique_event_id_;
 
   // Disallow copy/assign.
   MotionEventAndroid(const MotionEventAndroid& e);  // private ctor
   void operator=(const MotionEventAndroid&) = delete;
 };
 
 }  // namespace content
 
 #endif  // UI_EVENTS_ANDROID_MOTION_EVENT_ANDROID_H_