Support "display": "fullscreen" for sites added to the home screen.

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
index 7a35c67a8ce7a90cbdfc875aec890b77f31d55d4..4602ad331eea2e80475d08cf9c2c52f322ee14e4 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java
@@ -9,12 +9,14 @@ import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.graphics.drawable.Drawable;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.StrictMode;
 import android.os.SystemClock;
 import android.text.TextUtils;
 import android.view.LayoutInflater;
 import android.view.View;
+import android.view.View.OnSystemUiVisibilityChangeListener;
 import android.view.ViewGroup;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
@@ -30,6 +32,7 @@ import org.chromium.blink_public.platform.WebDisplayMode;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.TabState;
 import org.chromium.chrome.browser.document.DocumentUtils;
+import org.chromium.chrome.browser.fullscreen.ChromeFullscreenManager;
 import org.chromium.chrome.browser.metrics.WebappUma;
 import org.chromium.chrome.browser.tab.EmptyTabObserver;
 import org.chromium.chrome.browser.tab.Tab;
@@ -54,6 +57,16 @@ public class WebappActivity extends FullScreenActivity {
     private static final String TAG = "WebappActivity";
     private static final long MS_BEFORE_NAVIGATING_BACK_FROM_INTERSTITIAL = 1000;
 
+    private static final int ENTER_IMMERSIVE_MODE_DELAY_MILLIS = 300;
+    private static final int RESTORE_IMMERSIVE_MODE_DELAY_MILLIS = 3000;
+    private static final int IMMERSIVE_MODE_UI_FLAGS = View.SYSTEM_UI_FLAG_LAYOUT_STABLE
+            | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
+            | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
+            | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION // hide nav bar
+            | View.SYSTEM_UI_FLAG_FULLSCREEN // hide status bar
+            | View.SYSTEM_UI_FLAG_LOW_PROFILE
+            | View.SYSTEM_UI_FLAG_IMMERSIVE;
+
     private final WebappDirectoryManager mDirectoryManager;
 
     protected WebappInfo mWebappInfo;
@@ -68,6 +81,8 @@ public class WebappActivity extends FullScreenActivity {
 
     private Bitmap mLargestFavicon;
 
+    private Runnable mSetImmersiveRunnable;
+
     /**
      * Construct all the variables that shouldn't change.  We do it here both to clarify when the
      * objects are created and to ensure that they exist throughout the parallelized initialization
@@ -92,8 +107,6 @@ public class WebappActivity extends FullScreenActivity {
             mWebappInfo = newWebappInfo;
             resetSavedInstanceState();
             if (mIsInitialized) initializeUI(null);
-            // TODO(dominickn): send the web app into fullscreen if mDisplayMode is
-            // WebDisplayMode.Fullscreen. See crbug.com/581522
         }
     }
 
@@ -118,9 +131,10 @@ public class WebappActivity extends FullScreenActivity {
 
         getActivityTab().addObserver(createTabObserver());
         getActivityTab().getTabWebContentsDelegateAndroid().setDisplayMode(
-                WebDisplayMode.Standalone);
-        // TODO(dominickn): send the web app into fullscreen if mDisplayMode is
-        // WebDisplayMode.Fullscreen. See crbug.com/581522
+                mWebappInfo.displayMode());
+        if (mWebappInfo.displayMode() == WebDisplayMode.Fullscreen) {
+            enterImmersiveMode();
+        }
     }
 
     @Override
@@ -203,6 +217,65 @@ public class WebappActivity extends FullScreenActivity {
     }
 
     @Override
+    public void onWindowFocusChanged(boolean hasFocus) {
+        super.onWindowFocusChanged(hasFocus);
+
+        // Re-enter immersive mode after users switch back to this Activity.
+        if (hasFocus) {
+            asyncSetImmersive(ENTER_IMMERSIVE_MODE_DELAY_MILLIS);
+        }
+    }
+
+    /**
+     * Sets activity's decor view into an immersive mode.
+     * If immersive mode is not supported, this method no-ops.
+     */
+    private void enterImmersiveMode() {
+        // Immersive mode is only supported in API 19+.
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) return;
+
+        if (mSetImmersiveRunnable == null) {
+
+            final View decor = getWindow().getDecorView();
+
+            mSetImmersiveRunnable = new Runnable() {
+                @Override
+                public void run() {
+                    int currentFlags = decor.getSystemUiVisibility();
+                    int desiredFlags = currentFlags | IMMERSIVE_MODE_UI_FLAGS;
+                    if (currentFlags != desiredFlags) {
+                        decor.setSystemUiVisibility(desiredFlags);
+                    }
+                }
+            };
+
+            // When we enter immersive mode for the first time, register a
+            // SystemUiVisibilityChangeListener that restores immersive mode. This is necessary
+            // because user actions like focusing a keyboard will break out of immersive mode.
+            decor.setOnSystemUiVisibilityChangeListener(new OnSystemUiVisibilityChangeListener() {
+                @Override
+                public void onSystemUiVisibilityChange(int newFlags) {
+                    if ((newFlags & View.SYSTEM_UI_FLAG_FULLSCREEN) == 0) {
+                        asyncSetImmersive(RESTORE_IMMERSIVE_MODE_DELAY_MILLIS);
+                    }
+                }
+            });
+        }
+
+        asyncSetImmersive(ENTER_IMMERSIVE_MODE_DELAY_MILLIS);
+    }
+
+    /**
+     * This method no-ops before {@link enterImmersiveMode()) is called explicitly.
+     */
+    private void asyncSetImmersive(int delayInMills) {
+        if (mSetImmersiveRunnable == null) return;
+
+        mHandler.removeCallbacks(mSetImmersiveRunnable);
+        mHandler.postDelayed(mSetImmersiveRunnable, delayInMills);
+    }
+
+    @Override
     public void onResume() {
         if (!isFinishing()) {
             if (getIntent() != null) {
@@ -372,6 +445,24 @@ public class WebappActivity extends FullScreenActivity {
                 getActivityTab().getUrl(), getWebappInfo().uri().toString(), true);
     }
 
+    @Override
+    protected ChromeFullscreenManager createFullscreenManager() {
+        // Disable HTML5 fullscreen in PWA fullscreen mode.
+        return new ChromeFullscreenManager(this, false) {

[Ted C, 2017/02/17 05:51:50]

I'm also not against returning null here assuming we know mWebappInfo is
initialized properly before we get here.

Although if you navigate to a different domain, do we bring down the tiny little
location bar from the top in this mode?  If we return null, does that break (I
believe it uses fullscreen manager to do the showing/hiding of that these days).

If it does break, this seems ok to me (but i would hope it would since I
suggested it :-P)

[Leo, 2017/02/17 07:03:08]

I prefer your suggestion. Even returning null is cleaner and worked fine in my
testing (all existing code checked fullscreenManager before using), it still
looks not very safe. 

For the different domain bar. In the testing, I switched my test webapp's url in
fullscreen mode to google.com.au and the location bar was shown correctly
https://drive.google.com/a/chromium.org/file/d/0B7BQekACXW_VanNIUVJfN2tLQlU/v...

Thanks

+            @Override
+            public void setPersistentFullscreenMode(boolean enabled) {
+                if (mWebappInfo.displayMode() == WebDisplayMode.Fullscreen) return;
+                super.setPersistentFullscreenMode(enabled);
+            }
+
+            @Override
+            public boolean getPersistentFullscreenMode() {
+                if (mWebappInfo.displayMode() == WebDisplayMode.Fullscreen) return false;
+                return super.getPersistentFullscreenMode();
+            }
+        };
+    }
+
     protected TabObserver createTabObserver() {
         return new EmptyTabObserver() {