[WebLayer] Fix fullscreen videos having black bar on the bottom

The top bar was still taking up space even though it is not needed in
fullscreen. This also fixes a bug where pressing the back button did not
exit fullscreen in the shell.

Bug: 1029894
Change-Id: I215e8e1066670ba2e57d83114537b95c70186d99
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1946629Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720761}

weblayer/browser/tab_impl.cc

@@ -290,6 +290,8 @@ void TabImpl::RunFileChooser(
 }
 
 int TabImpl::GetTopControlsHeight() {
+  if (is_fullscreen_)
+    return 0;
 #if defined(OS_ANDROID)
   return top_controls_container_view_
              ? top_controls_container_view_->GetTopControlsHeight()

weblayer/shell/android/shell_apk/src/org/chromium/weblayer/shell/WebLayerShellActivity.java

@@ -62,6 +62,7 @@ public class WebLayerShellActivity extends FragmentActivity {
     private int mMainViewId;
     private ViewGroup mTopContentsContainer;
     private List<Tab> mPreviousTabList = new ArrayList<>();
+    private Runnable mExitFullscreenRunnable;
 
     @Override
     protected void onCreate(final Bundle savedInstanceState) {
@@ -181,6 +182,7 @@ public class WebLayerShellActivity extends FragmentActivity {
 
             @Override
             public void onEnterFullscreen(Runnable exitFullscreenRunnable) {
+                mExitFullscreenRunnable = exitFullscreenRunnable;
                 // This comes from Chrome code to avoid an extra resize.
                 final WindowManager.LayoutParams attrs = getWindow().getAttributes();
                 attrs.flags |= WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS;
@@ -200,6 +202,7 @@ public class WebLayerShellActivity extends FragmentActivity {
 
             @Override
             public void onExitFullscreen() {
+                mExitFullscreenRunnable = null;
                 View decorView = getWindow().getDecorView();
                 decorView.setSystemUiVisibility(mSystemVisibilityToRestore);
 
@@ -311,6 +314,10 @@ public class WebLayerShellActivity extends FragmentActivity {
 
     @Override
     public void onBackPressed() {
+        if (mExitFullscreenRunnable != null) {
+            mExitFullscreenRunnable.run();
+            return;
+        }
         if (mBrowser != null) {
             NavigationController controller = mBrowser.getActiveTab().getNavigationController();
             if (controller.canGoBack()) {