[Android] Implement scrollTo in terms of scrollBy

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

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 2ebfb8e79e70afba5d5de45144274eafaf540c7d..66a26291fe59ce6481d252ebb1abd7797b83fa39 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -1790,34 +1790,29 @@ public class ContentViewCore
      * are overridden, so that View's mScrollX and mScrollY will be unchanged at
      * (0, 0). This is critical for drawing ContentView correctly.
      */
-    public void scrollBy(int xPix, int yPix) {
-        if (mNativeContentViewCore != 0) {
-            nativeScrollBy(mNativeContentViewCore,
-                    SystemClock.uptimeMillis(), 0, 0, xPix, yPix);
-        }
+    public void scrollBy(float dxPix, float dyPix) {

[jdduke (slow), 2015/05/18 21:31:53]

We have to convert to float at some point anyway, don't care if we do that here
or with an internal helper |scrollByImpl| method.

[hush (inactive), 2015/05/19 00:33:23]

Hi Jared,
Just making sure I understand it.
Neither scrollBy nor scrollTo is used by Android webview. They are only
overriding the API defined in ContentView and only used by tests at this moment.
So this change won't affect webview.

https://code.google.com/p/chromium/codesearch#search/&q=%5CbscrollBy%5Cb%20f:...

Is there anything that I'm missing? How is it hooking up with the gamepad
controller?

+        if (mNativeContentViewCore == 0) return;
+        if (dxPix == 0 && dyPix == 0) return;
+        long time = SystemClock.uptimeMillis();
+        // It's a very real (and valid) possibility that a fling may still
+        // be active when programatically scrolling. Cancelling the fling in
+        // such cases ensures a consistent gesture event stream.
+        if (mPotentiallyActiveFlingCount > 0) nativeFlingCancel(mNativeContentViewCore, time);
+        nativeScrollBegin(mNativeContentViewCore, time, 0, 0, -dxPix, -dyPix);
+        nativeScrollBy(mNativeContentViewCore, time, 0, 0, dxPix, dyPix);
+        nativeScrollEnd(mNativeContentViewCore, time);
     }
 
     /**
      * @see View#scrollTo(int, int)
      */
-    public void scrollTo(int xPix, int yPix) {
+    public void scrollTo(float xPix, float yPix) {
         if (mNativeContentViewCore == 0) return;
         final float xCurrentPix = mRenderCoordinates.getScrollXPix();
         final float yCurrentPix = mRenderCoordinates.getScrollYPix();
         final float dxPix = xPix - xCurrentPix;
         final float dyPix = yPix - yCurrentPix;
-        if (dxPix != 0 || dyPix != 0) {
-            long time = SystemClock.uptimeMillis();
-            // It's a very real (and valid) possibility that a fling may still
-            // be active when programatically scrolling. Cancelling the fling in
-            // such cases ensures a consistent gesture event stream.
-            if (mPotentiallyActiveFlingCount > 0) nativeFlingCancel(mNativeContentViewCore, time);
-            nativeScrollBegin(mNativeContentViewCore, time,
-                    xCurrentPix, yCurrentPix, -dxPix, -dyPix);
-            nativeScrollBy(mNativeContentViewCore,
-                    time, xCurrentPix, yCurrentPix, dxPix, dyPix);
-            nativeScrollEnd(mNativeContentViewCore, time);
-        }
+        scrollBy(dxPix, dyPix);
     }
 
     // NOTE: this can go away once ContentView.getScrollX() reports correct values.