Revert "[synthesized scroll] Fix wheel-event precision on android."

This reverts commit bad70cb2.

Reason for revert: SyntheticInputTest.SlowSmoothScrollWheel is
still flaky on Android. https://crbug.com/1086450

Original change's description:
> [synthesized scroll] Fix wheel-event precision on android.
> 
> Update API to set fractional wheel deltas on android, and remove the
> code that explicitly used to remove precision.
> 
> BUG=1085890
> 
> Change-Id: Ifd18df07637b2fa28288de62bf538f65f7a4d0a7
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2213406
> Commit-Queue: Sadrul Chowdhury <sadrul@chromium.org>
> Reviewed-by: David Bokan <bokan@chromium.org>
> Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#771639}

TBR=sadrul@chromium.org,yfriedman@chromium.org,bokan@chromium.org,nzolghadr@chromium.org

Change-Id: Ib671a1db643144448de054fc93b43a2ad87e4805
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1085890, 1086450
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2215824Reviewed-by: Alex Ilin <alexilin@chromium.org>
Commit-Queue: Alex Ilin <alexilin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771760}

content/browser/renderer_host/input/synthetic_gesture_target_android.cc

@@ -38,8 +38,8 @@ SyntheticGestureTargetAndroid::SyntheticGestureTargetAndroid(
 SyntheticGestureTargetAndroid::~SyntheticGestureTargetAndroid() = default;
 
 void SyntheticGestureTargetAndroid::TouchSetPointer(int index,
-                                                    float x,
-                                                    float y,
+                                                    int x,
+                                                    int y,
                                                     int id) {
   TRACE_EVENT0("input", "SyntheticGestureTargetAndroid::TouchSetPointer");
   JNIEnv* env = base::android::AttachCurrentThread();
@@ -48,10 +48,10 @@ void SyntheticGestureTargetAndroid::TouchSetPointer(int index,
       env, java_ref_, index, x * scale_factor, y * scale_factor, id);
 }
 
-void SyntheticGestureTargetAndroid::TouchSetScrollDeltas(float x,
-                                                         float y,
-                                                         float dx,
-                                                         float dy) {
+void SyntheticGestureTargetAndroid::TouchSetScrollDeltas(int x,
+                                                         int y,
+                                                         int dx,
+                                                         int dy) {
   TRACE_EVENT0("input", "SyntheticGestureTargetAndroid::TouchSetScrollDeltas");
   JNIEnv* env = base::android::AttachCurrentThread();
 

content/browser/renderer_host/input/synthetic_gesture_target_android.h

@@ -47,8 +47,8 @@ class SyntheticGestureTargetAndroid : public SyntheticGestureTargetBase {
   float GetMinScalingSpanInDips() const override;
 
  private:
-  void TouchSetPointer(int index, float x, float y, int id);
-  void TouchSetScrollDeltas(float x, float y, float dx, float dy);
+  void TouchSetPointer(int index, int x, int y, int id);
+  void TouchSetScrollDeltas(int x, int y, int dx, int dy);
   void TouchInject(MotionEventAction action,
                    int pointer_count,
                    base::TimeTicks time);

content/browser/renderer_host/input/synthetic_input_browsertest.cc

@@ -157,9 +157,15 @@ IN_PROC_BROWSER_TEST_F(SyntheticInputTest, SmoothScrollWheel) {
                         "document.scrollingElement.scrollTop"));
 }
 
+// Wheel events lose precision on android (crbug.com/934649)
+#if defined(OS_ANDROID)
+#define MAYBE_SlowSmoothScrollWheel DISABLED_SlowSmoothScrollWheel
+#else
+#define MAYBE_SlowSmoothScrollWheel SlowSmoothScrollWheel
+#endif
 // This test ensures that slow synthetic wheel scrolling does not lose precision
 // over time.
-IN_PROC_BROWSER_TEST_F(SyntheticInputTest, SlowSmoothScrollWheel) {
+IN_PROC_BROWSER_TEST_F(SyntheticInputTest, MAYBE_SlowSmoothScrollWheel) {
   LoadURL(R"HTML(
     data:text/html;charset=utf-8,
     <!DOCTYPE html>
@@ -193,18 +199,14 @@ IN_PROC_BROWSER_TEST_F(SyntheticInputTest, SlowSmoothScrollWheel) {
 
   runner_ = std::make_unique<base::RunLoop>();
 
-  auto* web_contents = shell()->web_contents();
-  RenderFrameSubmissionObserver scroll_offset_wait(web_contents);
+  RenderFrameSubmissionObserver scroll_offset_wait(shell()->web_contents());
   std::unique_ptr<SyntheticSmoothScrollGesture> gesture(
       new SyntheticSmoothScrollGesture(params));
   GetRenderWidgetHost()->QueueSyntheticGesture(
       std::move(gesture),
       base::BindOnce(&SyntheticInputTest::OnSyntheticGestureCompleted,
                      base::Unretained(this)));
-  float device_scale_factor =
-      web_contents->GetRenderWidgetHostView()->GetDeviceScaleFactor();
-  scroll_offset_wait.WaitForScrollOffset(
-      gfx::Vector2dF(0.f, 1024.f * device_scale_factor));
+  scroll_offset_wait.WaitForScrollOffset(gfx::Vector2dF(0.f, 1024.f));
 
   EXPECT_EQ(1024, EvalJs(shell()->web_contents(),
                          "document.scrollingElement.scrollTop"));

content/browser/renderer_host/input/synthetic_smooth_move_gesture.cc

@@ -172,6 +172,23 @@ void SyntheticSmoothMoveGesture::ForwardMouseWheelInputEvents(
       base::TimeTicks event_timestamp = ClampTimestamp(timestamp);
       gfx::Vector2dF delta = GetPositionDeltaAtTime(event_timestamp) -
                              current_move_segment_total_delta_;
+
+      // Android MotionEvents that carry mouse wheel ticks and the tick
+      // granularity. Since it's not easy to change this granularity, it means
+      // we can only scroll in terms of number of these ticks. Note also: if
+      // the delta is smaller than one tick size we wont send an event or
+      // accumulate it in current_move_segment_total_delta_ so that we don't
+      // consider that delta applied. If we did, slow scrolls would be entirely
+      // lost since we'd send 0 ticks in each event but assume delta was
+      // applied.
+      int pixels_per_wheel_tick = target->GetMouseWheelMinimumGranularity();
+      if (pixels_per_wheel_tick) {
+        int wheel_ticks_x = static_cast<int>(delta.x() / pixels_per_wheel_tick);
+        int wheel_ticks_y = static_cast<int>(delta.y() / pixels_per_wheel_tick);
+        delta = gfx::Vector2dF(wheel_ticks_x * pixels_per_wheel_tick,
+                               wheel_ticks_y * pixels_per_wheel_tick);
+      }
+
       if (delta.x() || delta.y()) {
         blink::WebMouseWheelEvent::Phase phase =
             needs_scroll_begin_ ? blink::WebMouseWheelEvent::kPhaseBegan

content/public/android/java/src/org/chromium/content/browser/MotionEventSynthesizerImpl.java

@@ -44,7 +44,7 @@ public class MotionEventSynthesizerImpl implements MotionEventSynthesizer {
      * @param toolType ToolType property of the point.
      */
     @Override
-    public void setPointer(int index, float x, float y, int id, int toolType) {
+    public void setPointer(int index, int x, int y, int id, int toolType) {
         assert (0 <= index && index < MAX_NUM_POINTERS);
 
         PointerCoords coords = new PointerCoords();
@@ -67,7 +67,7 @@ public class MotionEventSynthesizerImpl implements MotionEventSynthesizer {
      * @param x Y coordinate of the point.
      * @param id Id property of the point.
      */
-    public void setPointer(int index, float x, float y, int id) {
+    public void setPointer(int index, int x, int y, int id) {
         setPointer(index, x, y, id, MotionEvent.TOOL_TYPE_UNKNOWN);
     }
 
@@ -79,7 +79,7 @@ public class MotionEventSynthesizerImpl implements MotionEventSynthesizer {
      * @param dx Delta along the X coordinate.
      * @param dy Delta along the Y coordinate.
      */
-    public void setScrollDeltas(float x, float y, float dx, float dy) {
+    public void setScrollDeltas(int x, int y, int dx, int dy) {
         setPointer(0, x, y, 0);
         mPointerCoords[0].setAxisValue(MotionEvent.AXIS_HSCROLL, dx);
         mPointerCoords[0].setAxisValue(MotionEvent.AXIS_VSCROLL, dy);

content/public/android/java/src/org/chromium/content/browser/SyntheticGestureTarget.java

@@ -31,12 +31,12 @@ public class SyntheticGestureTarget {
     }
 
     @CalledByNative
-    private void setPointer(int index, float x, float y, int id) {
+    private void setPointer(int index, int x, int y, int id) {
         mMotionEventSynthesizer.setPointer(index, x, y, id);
     }
 
     @CalledByNative
-    private void setScrollDeltas(float x, float y, float dx, float dy) {
+    private void setScrollDeltas(int x, int y, int dx, int dy) {
         mMotionEventSynthesizer.setScrollDeltas(x, y, dx, dy);
     }
 }

content/public/android/java/src/org/chromium/content_public/browser/MotionEventSynthesizer.java

@@ -25,7 +25,7 @@ public interface MotionEventSynthesizer {
      * @param id Id property of the point.
      * @param toolType ToolType property of the point.
      */
-    void setPointer(int index, float x, float y, int id, int toolType);
+    void setPointer(int index, int x, int y, int id, int toolType);
 
     /**
      * Injects a synthetic action with the preset points and delta.