Implement the new Photo picker, part one.

ui/android/java/src/org/chromium/ui/UiUtils.java

Index: ui/android/java/src/org/chromium/ui/UiUtils.java
diff --git a/ui/android/java/src/org/chromium/ui/UiUtils.java b/ui/android/java/src/org/chromium/ui/UiUtils.java
index 61fa37f2cf3329ee49812dae8339a9d63282d62e..331028961d9c244cb9d873ff15435327fcbfc085 100644
--- a/ui/android/java/src/org/chromium/ui/UiUtils.java
+++ b/ui/android/java/src/org/chromium/ui/UiUtils.java
@@ -56,6 +56,9 @@ public class UiUtils {
     /** A delegate that allows disabling keyboard visibility detection. */
     private static KeyboardShowingDelegate sKeyboardShowingDelegate;
 
+    /** A delegate for the photo picker. */
+    private static PhotoPickerDelegate sPhotoPickerDelegate;
+
     /**
      * A delegate that can be implemented to override whether or not keyboard detection will be
      * used.
@@ -71,6 +74,25 @@ public class UiUtils {
     }
 
     /**
+     * A delegate interface for the photo picker.
+     */
+    public interface PhotoPickerDelegate {
+        /**
+         * Called to display the photo picker.
+         * @param context  The context to use.
+         * @param listener The listener that will be notified of the selection.

[Theresa, 2017/03/15 15:56:32]

nit: ... notified of the action the user took in the picker?

[Finnur, 2017/03/16 11:38:04]

Done.

+         * @param allowMultiple Whether the dialog should allow multiple images to be selected.
+         */
+        void showPhotoPicker(
+                Context context, OnPhotoPickerListener listener, boolean allowMultiple);
+
+        /**
+         * Called when the photo picker dialog should be dismissed.
+         */
+        void dismissPhotoPicker();
+    }
+
+    /**
      * Allows setting a delegate to override the default software keyboard visibility detection.
      * @param delegate A {@link KeyboardShowingDelegate} instance.
      */
@@ -79,6 +101,14 @@ public class UiUtils {
     }
 
     /**
+     * Allows setting a delegate to override the default Android stock photo picker.
+     * @param delegate A {@link PhotoPickerDelegate} instance.
+     */
+    public static void setPhotoPickerDelegate(PhotoPickerDelegate delegate) {
+        sPhotoPickerDelegate = delegate;
+    }
+
+    /**
      * Shows the software keyboard if necessary.
      * @param view The currently focused {@link View}, which would receive soft keyboard input.
      */
@@ -170,6 +200,20 @@ public class UiUtils {
         return locales;
     }
 
+    // PhotoPickerDelegate:
+
+    public static boolean showPhotoPicker(

[Theresa, 2017/03/15 15:56:32]

nit: let's move the setPhotoPickerDelegate() method above these two to keep them
grouped together and avoid splitting up setKeyboardShowingDelegate and the
keyboard methods.

[Finnur, 2017/03/16 11:38:04]

Oh, I didn't realize these were keyboard methods below. Done.

[Theresa, 2017/03/16 16:26:17]

I don't think insertBefore, et al. are keyboard methods. I meant keeping
setKeyboardShowingDelegate grouped with showKeyboard.

+            Context context, OnPhotoPickerListener listener, boolean allowMultiple) {
+        if (sPhotoPickerDelegate == null) return false;
+        sPhotoPickerDelegate.showPhotoPicker(context, listener, allowMultiple);
+        return true;
+    }
+
+    public static void dismissPhotoPicker() {

[Theresa, 2017/03/15 15:56:32]

This method and the one above need JavaDocs.

[Finnur, 2017/03/16 11:38:04]

Done.

+        if (sPhotoPickerDelegate == null) return;
+        sPhotoPickerDelegate.dismissPhotoPicker();

[Theresa, 2017/03/15 15:56:32]

In Android N+ multi-window, will it be possible for the user to have two photo
pickers displayed at once? If so, how will we know which one is being dismissed?
If not, how will we prevent two from being created?

[Finnur, 2017/03/16 11:38:04]

That's a good point. I'll take it into consideration.

My initial reaction (without seeing how the multi-window works) is that we could
make it so that only one dialog is open at a time, but I need to research this
better. Shouldn't block this CL, though.

+    }
+
     /**
      * Inserts a {@link View} into a {@link ViewGroup} after directly before a given {@View}.
      * @param container The {@link View} to add newView to.