Fix status bar visibility issue on pre-Marshmallow devices

remoting/android/java/src/org/chromium/chromoting/Desktop.java

Index: remoting/android/java/src/org/chromium/chromoting/Desktop.java
diff --git a/remoting/android/java/src/org/chromium/chromoting/Desktop.java b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
index 887d16b9c9de48c2bec201aa7d6c6d6b2c264c88..11915c9e10bef2fc49f1150eb6280781c0d31a5e 100644
--- a/remoting/android/java/src/org/chromium/chromoting/Desktop.java
+++ b/remoting/android/java/src/org/chromium/chromoting/Desktop.java
@@ -77,6 +77,9 @@ public class Desktop
     /** Flag to indicate whether the current activity is switching to Cardboard desktop activity. */
     private boolean mSwitchToCardboardDesktopActivity;
 
+    /** Flag to indicate whether to manually hide the system UI when the OSK is dismissed. */

[Lambros, 2016/01/29 19:09:57]

Avoid OSK abbreviation, maybe just "keyboard" or "Soft Input UI" instead?

[joedow, 2016/01/29 19:31:17]

Done.

+    private boolean mHideSystemUIOnOskDismiss = false;
+
     /** Indicates whether a Soft Input UI (such as a keyboard) is visible. */
     private boolean mSoftInputVisible = false;
 
@@ -387,6 +390,8 @@ public class Desktop
     }
 
     public void showActionBar() {
+        mHideSystemUIOnOskDismiss = false;
+
         // Request exit from any fullscreen mode. The action-bar controls will be shown in response
         // to the SystemUiVisibility notification. The visibility of the action-bar should be tied
         // to the fullscreen state of the system, so there's no need to explicitly show it here.
@@ -439,6 +444,12 @@ public class Desktop
         // and still allow the system to hide the ActionBar normally when no keyboard is present.
         if (mSoftInputVisible) {
             hideActionBarWithoutSystemUi();
+
+            // Android OSes prior to Marshmallow do not call onSystemUiVisibilityChange after the
+            // OSK is dismissed if the user has interacted with the status bar.

[Lambros, 2016/01/29 19:09:57]

This comment seems to contradict the first sentence in the comment above? Are
you saying that the OS will not call onSystemUiVisibilityChange() until the
keyboard has been dismissed; and on pre-M versions, it doesn't even get called
at all?

I think the problem is slightly different than what the comment indicates. You
say that we don't get the full-screen notification, but I think perhaps the
system doesn't even go into fullscreen. That's the real problem isn't it - the
system is out of full-screen, but our toolbar gets hidden, so the user has no
way of revealing the toolbar?

[joedow, 2016/01/29 19:31:17]

It doesn't contradict the sentence, it is documenting a complication due to the
older OS behavior.  onSystemUiVisibilityChange() is called for all OSes except
when the user interacts with the stats bar on pre-Marshmallow OSes.

For the second comment, I don't think it is a fullscreen issue.  It seems to me
that the OS acts like it is in immersive sticky mode even though that flag is
not specified.

+            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
+                mHideSystemUIOnOskDismiss = true;
+            }
         }
     }
 
@@ -534,6 +545,20 @@ public class Desktop
                 mSoftInputVisible = (bottom < mMaxBottomValue);
                 mRemoteHostDesktop.onSoftInputMethodVisibilityChanged(
                         mSoftInputVisible, new Rect(left, top, right, bottom));
+
+                if (!mSoftInputVisible && mHideSystemUIOnOskDismiss) {
+                    // Queue a task which will run after the current action (OSK dismiss) has
+                    // completed, otherwise the hide request will not take effect.
+                    new Handler().post(new Runnable() {
+                        @Override
+                        public void run() {
+                            if (mHideSystemUIOnOskDismiss) {

[Lambros, 2016/01/29 19:09:57]

Why do you need to check this flag again? You already check it in the previous
if statement.

[joedow, 2016/01/29 19:31:17]

I am checking it here because this task is appended to the work queue.  *If* a
pending call to 'showActionBar()' were ahead of this task then the show would be
negated by this call.  Instead I check the value of the flag inside the queued
task to ensure it is still the intended behavior when the task is executed.

If the task were queued multiple times (due to a bug) we would still only
execute the hide once.

+                                mHideSystemUIOnOskDismiss = false;
+                                hideActionBar();
+                            }
+                        }
+                    });
+                }
             }
         });
     }