Add debugging messages for selection handles and magnifier

These were frequently used debugging messages when investigating
magnifier and selection handle issues, so adding the code controlled
by a hard-coded flag.

Bug: 1134492
Change-Id: I801492d1a47089247237d459ae33acc53bd9eb41
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2453789Reviewed-by: Shimi Zhang <ctzsm@chromium.org>
Commit-Queue: Changwan Ryu <changwan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814312}

content/public/android/java/src/org/chromium/content/browser/selection/MagnifierAnimator.java

@@ -7,11 +7,16 @@ package org.chromium.content.browser.selection;
 import android.animation.ValueAnimator;
 import android.view.animation.LinearInterpolator;
 
+import org.chromium.base.Log;
+
 /**
  * MagnifierAnimator adds animation to MagnifierWrapper when there is a change in y direction.
  * MagnifierWrapper class isolated P APIs out so we could write test for MagnifierAnimator.
  */
 public class MagnifierAnimator implements SelectionInsertionHandleObserver {
+    private static final boolean DEBUG = false;
+    private static final String TAG = "Magnifier";
+
     private static final long DURATION_MS = 100;
 
     private MagnifierWrapper mMagnifier;
@@ -46,6 +51,11 @@ public class MagnifierAnimator implements SelectionInsertionHandleObserver {
     @Override
     public void handleDragStartedOrMoved(float x, float y) {
         if (!mMagnifier.isAvailable()) return;
+        if (DEBUG) {
+            Log.i(TAG,
+                    "handleDragStartedOrMoved: "
+                            + "(" + x + ", " + y + ")");
+        }
         // We only do animation if this is not the first time to show magnifier and y coordinate
         // is different from last target.
         if (mMagnifierIsShowing && y != mTargetY) {

content/public/android/java/src/org/chromium/content/browser/selection/MagnifierWrapperImpl.java

@@ -8,11 +8,16 @@ import android.annotation.SuppressLint;
 import android.view.View;
 import android.widget.Magnifier;
 
+import org.chromium.base.Log;
+
 /**
  * Implements MagnifierWrapper interface.
  */
 @SuppressLint("NewApi") // Magnifier requires API level 28.
 public class MagnifierWrapperImpl implements MagnifierWrapper {
+    private static final boolean DEBUG = false;
+    private static final String TAG = "Magnifier";
+
     private Magnifier mMagnifier;
     private SelectionPopupControllerImpl.ReadbackViewCallback mCallback;
 
@@ -28,12 +33,14 @@ public class MagnifierWrapperImpl implements MagnifierWrapper {
         View view = mCallback.getReadbackView();
         if (view == null) return;
         if (mMagnifier == null) mMagnifier = new Magnifier(view);
+        if (DEBUG) Log.i(TAG, "show (" + x + ", " + y + ")");
         mMagnifier.show(x, y);
     }
 
     @Override
     public void dismiss() {
         if (mMagnifier != null) {
+            if (DEBUG) Log.i(TAG, "dismiss");
             mMagnifier.dismiss();
             mMagnifier = null;
         }

content/public/android/java/src/org/chromium/content/browser/selection/SelectionPopupControllerImpl.java

@@ -80,6 +80,7 @@ public class SelectionPopupControllerImpl extends ActionModeCallbackHelper
         implements ImeEventObserver, SelectionPopupController, WindowEventObserver, HideablePopup,
                    ContainerViewObserver, UserData {
     private static final String TAG = "SelectionPopupCtlr"; // 20 char limit
+    private static final boolean DEBUG = false;
 
     /**
      * Android Intent size limitations prevent sending over a megabyte of data. Limit
@@ -1286,6 +1287,11 @@ public class SelectionPopupControllerImpl extends ActionModeCallbackHelper
     @CalledByNative
     void onSelectionEvent(
             @SelectionEventType int eventType, int left, int top, int right, int bottom) {
+        if (DEBUG) {
+            Log.i(TAG,
+                    "onSelectionEvent: " + eventType + "[(" + left + ", " + top + ")-(" + right
+                            + ", " + bottom + ")]");
+        }
         // Ensure the provided selection coordinates form a non-empty rect, as required by
         // the selection action mode.
         // NOTE: the native side ensures the rectangle is not empty, but that's done using floating