Disable fullscreen video in OverlayPanels

This change hides the fullscreen button for videos in Reader Mode
and uses an empty implementation of ContentVideoViewEmbedder in case
it is somehow triggered. This is a temporary measure until a proper
fullscreen handler can be implemented.

BUG=581943

Review URL: https://codereview.chromium.org/1674753002

Cr-Commit-Position: refs/heads/master@{#374830}

chrome/android/java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java

@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.compositor.bottombar;
 
 import android.app.Activity;
 import android.content.Context;
+import android.view.View;
 import android.view.View.MeasureSpec;
 
 import org.chromium.base.ActivityState;
@@ -17,6 +18,7 @@ import org.chromium.chrome.browser.compositor.bottombar.OverlayPanelManager.Pane
 import org.chromium.chrome.browser.compositor.layouts.LayoutUpdateHost;
 import org.chromium.chrome.browser.compositor.scene_layer.SceneLayer;
 import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.content.browser.ContentVideoViewEmbedder;
 import org.chromium.content.browser.ContentViewClient;
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content_public.common.TopControlsState;
@@ -334,6 +336,27 @@ public class OverlayPanel extends OverlayPanelAnimation implements ActivityState
                             MeasureSpec.EXACTLY);
                 }
             }
+
+            @Override
+            public ContentVideoViewEmbedder getContentVideoViewEmbedder() {
+                // TODO(mdjones): Possibly enable fullscreen video in overlay panels rather than
+                // passing an empty implementation.
+                return new ContentVideoViewEmbedder() {
+                    @Override
+                    public void enterFullscreenVideo(View view) {}
+
+                    @Override
+                    public void exitFullscreenVideo() {}
+
+                    @Override
+                    public View getVideoLoadingProgressView() {
+                        return null;
+                    }
+
+                    @Override
+                    public void setSystemUiVisibility(boolean enterFullscreen) {}
+                };
+            }
         });
 
         return content;

components/dom_distiller/core/css/distilledpage.css

@@ -255,6 +255,10 @@ h6 {
   color: #55F;
 }
 
+video::-webkit-media-controls-fullscreen-button {
+  display: none;
+}
+
 #closeReaderView {
   /*
   TODO(mdjones): Remove the "display: none;" style when the Reader Mode bar