VR: Work around GVR UI not updating when density changes.

This is a hack around b/66493165 that should be removed when a GVR fix
is released. We manually find the views GVR adds to the hierarchy and
resize them/re-generate their Drawables for the new density.

Bug: 767603
Change-Id: Iacf40d81281d2e1a9423c095935d861b15be68fa
Reviewed-on: https://chromium-review.googlesource.com/682107Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504479}

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java

@@ -1711,8 +1711,11 @@ public abstract class ChromeActivity extends AsyncInitializationActivity
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
             if (newConfig.densityDpi != mDensityDpi) {
+                if (!VrShellDelegate.onDensityChanged(mDensityDpi, newConfig.densityDpi)) {
+                    recreate();
+                    return;
+                }
                 mDensityDpi = newConfig.densityDpi;
-                if (!VrShellDelegate.onDensityChanged()) recreate();
             }
         }
 

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShell.java

@@ -85,4 +85,9 @@ public interface VrShell {
      *  Triggers VrShell to navigate backward.
      */
     void navigateBack();
+
+    /**
+     * Should be called when the density changes. Updates UI in response to the new density.
+     */
+    void onDensityChanged(float oldDpi, float newDpi);
 }

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java

@@ -423,7 +423,7 @@ public class VrShellDelegate
      * @return Whether VrShellDelegate handled the density change. If the density change is
      * unhandled, the Activity should be recreated in order to handle the change.
      */
-    public static boolean onDensityChanged() {
+    public static boolean onDensityChanged(float oldDpi, float newDpi) {
         if (sInstance == null) return false;
         // If density changed while in VR, we expect a second density change to restore the density
         // to what it previously was when we exit VR. We shouldn't have to recreate the activity as
@@ -434,6 +434,7 @@ public class VrShellDelegate
             return true;
         }
         if (sInstance.mInVr || sInstance.mDonSucceeded) {
+            sInstance.onDensityChangedInternal(oldDpi, newDpi);
             sInstance.mDensityChanged = true;
             return true;
         }
@@ -1517,6 +1518,10 @@ public class VrShellDelegate
         mRestoreSystemUiVisibilityFlag = -1;
     }
 
+    private void onDensityChangedInternal(float oldDpi, float newDpi) {
+        if (mVrShell != null) mVrShell.onDensityChanged(oldDpi, newDpi);
+    }
+
     /**
      * Clean up VrShell, and associated native objects.
      */

chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellImpl.java

@@ -14,8 +14,12 @@ import android.view.Surface;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 import android.view.View;
+import android.view.ViewGroup;
+import android.view.ViewGroup.LayoutParams;
 import android.view.ViewTreeObserver.OnPreDrawListener;
 import android.widget.FrameLayout;
+import android.widget.ImageButton;
+import android.widget.RelativeLayout;
 
 import com.google.vr.ndk.base.AndroidCompat;
 import com.google.vr.ndk.base.GvrLayout;
@@ -609,6 +613,46 @@ public class VrShellImpl
         return this;
     }
 
+    @Override
+    public void onDensityChanged(float oldDpi, float newDpi) {
+        // TODO(mthiesse, crbug.com/767603): Remove this workaround for b/66493165.
+        // This is extremely hacky. The GvrUiLayout doesn't update in response to density changes,
+        // so we manually go in and scale their elements to be the correct size (though due to the
+        // scaling they don't actually look pixel-perfectly identical to what they should be).
+        // These elements are dynamically loaded and inserted into the view hierarchy so we don't
+        // have IDs for them that we can look up.
+        try {
+            float scale = newDpi / oldDpi;
+            ViewGroup gvrLayoutImpl = (ViewGroup) getContainer().getChildAt(0);
+            RelativeLayout relativeLayout = (RelativeLayout) gvrLayoutImpl.getChildAt(1);
+
+            ImageButton x_button = (ImageButton) relativeLayout.getChildAt(0);
+            RelativeLayout alignment_marker = (RelativeLayout) relativeLayout.getChildAt(1);
+            ImageButton settings_button = (ImageButton) relativeLayout.getChildAt(2);
+
+            ViewGroup.LayoutParams params = alignment_marker.getLayoutParams();
+            params.width = (int) (params.width * scale);
+            params.height = (int) (params.height * scale);
+            alignment_marker.setLayoutParams(params);
+
+            int padding = (int) (x_button.getPaddingLeft() * scale);
+
+            x_button.setImageDrawable(x_button.getDrawable().getConstantState().newDrawable(
+                    mActivity.getResources()));
+            x_button.setPadding(padding, padding, padding, padding);
+
+            settings_button.setImageDrawable(
+                    settings_button.getDrawable().getConstantState().newDrawable(
+                            mActivity.getResources()));
+            settings_button.setPadding(padding, padding, padding, padding);
+        } catch (Throwable e) {
+            // Ignore any errors. We're working around a bug in dynamically loaded code, so if it
+            // goes wrong that means the loaded code changed. ¯\_(ツ)_/¯
+            // In the worst case the close and settings buttons won't be drawn for the correct
+            // density.
+        }
+    }
+
     @Override
     public void surfaceCreated(SurfaceHolder holder) {
         nativeSetSurface(mNativeVrShell, holder.getSurface());