[Android] Allow specifying the progress component of the toolbar as a separate texture.

chrome/android/java/src/org/chromium/chrome/browser/widget/SmoothProgressBar.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/SmoothProgressBar.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/SmoothProgressBar.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/SmoothProgressBar.java
index 1e7542724d2ed29accab5b5116be88da52908547..c084b619f7f28570e4a5321ba2185211fa5ab3a7 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/widget/SmoothProgressBar.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/SmoothProgressBar.java
@@ -9,6 +9,8 @@ import android.util.AttributeSet;
 import android.widget.ProgressBar;
 
 import org.chromium.base.ApiCompatibilityUtils;
+import org.chromium.base.ObserverList;
+import org.chromium.base.ObserverList.RewindableIterator;
 
 /**
  * A progress bar that smoothly animates incremental updates.
@@ -18,11 +20,32 @@ import org.chromium.base.ApiCompatibilityUtils;
  * {@link #setProgress(int)}.
  */
 public class SmoothProgressBar extends ProgressBar {
+
+    /**
+     * Allows observation of visual changes to the progress bar.
+     */
+    public interface ProgressChangeListener {
+        /**
+         * Triggered when the visible progress has changed.
+         * @param progress The current progress value.
+         */
+        void onProgressChanged(int progress);
+
+        /**
+         * Triggered when the visibility of the progress bar has changed.
+         * @param visibility The visibility of the progress bar.
+         */
+        void onProgressVisibilityChanged(int visibility);
+    }
+
     private static final int MAX = 100;
 
     // The amount of time between subsequent progress updates. 16ms is chosen to make 60fps.
     private static final long PROGRESS_UPDATE_DELAY_MS = 16;
 
+    private final ObserverList<ProgressChangeListener> mObservers;
+    private final RewindableIterator<ProgressChangeListener> mObserversIterator;
+
     private boolean mIsAnimated = false;
     private int mTargetProgress;
 
@@ -55,6 +78,26 @@ public class SmoothProgressBar extends ProgressBar {
     public SmoothProgressBar(Context context, AttributeSet attrs) {
         super(context, attrs);
         setMax(MAX * mResolutionMutiplier);
+
+        mObservers = new ObserverList<ProgressChangeListener>();
+        mObserversIterator = mObservers.rewindableIterator();
+
+    }
+
+    /**
+     * Adds an observer to be notified of progress changes.
+     * @param observer The observer to be added.
+     */
+    public void addProgressChangeListener(ProgressChangeListener observer) {
+        mObservers.addObserver(observer);
+    }
+
+    /**
+     * Removes an observer to be notified of progress changes.
+     * @param observer The observer to be removed.
+     */
+    public void removeProgressChangeListener(ProgressChangeListener observer) {
+        mObservers.removeObserver(observer);
     }
 
     @Override
@@ -92,5 +135,22 @@ public class SmoothProgressBar extends ProgressBar {
      */
     protected void setProgressInternal(int progress) {
         super.setProgress(progress);
+
+        if (mObserversIterator != null) {
+            for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+                mObserversIterator.next().onProgressChanged(progress);
+            }
+        }
+    }
+
+    @Override
+    public void setVisibility(int visibility) {
+        super.setVisibility(visibility);
+
+        if (mObserversIterator != null) {
+            for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+                mObserversIterator.next().onProgressVisibilityChanged(visibility);
+            }
+        }
     }
 }