Rename AbstractDrawingPreview.onDraw to drawPreview

This is because the android lint warns calling a method onDraw(Canvas)
from View.onDraw(Canvas).

Change-Id: I4f54996da5454d9a8c4ef43fbbcaec37724fb20e

java/src/com/android/inputmethod/keyboard/internal/AbstractDrawingPreview.java

@@ -39,7 +39,7 @@ public abstract class AbstractDrawingPreview {
      * Draws the preview
      * @param canvas The canvas where the preview is drawn.
      */
-    public abstract void onDraw(final Canvas canvas);
+    public abstract void drawPreview(final Canvas canvas);
 
     /**
      * Set the position of the preview.

java/src/com/android/inputmethod/keyboard/internal/GestureFloatingPreviewText.java

@@ -130,7 +130,7 @@ public class GestureFloatingPreviewText extends AbstractDrawingPreview {
      * @param canvas The canvas where preview text is drawn.
      */
     @Override
-    public void onDraw(final Canvas canvas) {
+    public void drawPreview(final Canvas canvas) {
         if (!isPreviewEnabled() || mSuggestedWords.isEmpty()
                 || TextUtils.isEmpty(mSuggestedWords.getWord(0))) {
             return;

java/src/com/android/inputmethod/keyboard/internal/PreviewPlacerView.java

@@ -220,7 +220,7 @@ public final class PreviewPlacerView extends RelativeLayout {
                 // rectangle on the canvas.
             }
         }
-        mGestureFloatingPreviewText.onDraw(canvas);
+        mGestureFloatingPreviewText.drawPreview(canvas);
         if (mShowSlidingKeyInputPreview) {
             drawSlidingKeyInputPreview(canvas);
         }