Propagate fullscreen state to interstitial's when shown.

Without this interstitials will be able to be scroll off the top controls,
which is definitely not the correct behavior.

BUG=474795

Review URL: https://codereview.chromium.org/1070293002

Cr-Commit-Position: refs/branch-heads/2357@{#34}
Cr-Branched-From: 59d4494-refs/heads/master@{#323860}

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

@@ -652,6 +652,8 @@ public void didAttachInterstitialPage() {
             for (TabObserver observer : mObservers) {
                 observer.onDidAttachInterstitialPage(Tab.this);
             }
+
+            updateFullscreenEnabledState();
         }
 
         @Override
@@ -661,6 +663,8 @@ public void didDetachInterstitialPage() {
             for (TabObserver observer : mObservers) {
                 observer.onDidDetachInterstitialPage(Tab.this);
             }
+
+            updateFullscreenEnabledState();
         }
 
         @Override
@@ -2425,6 +2429,7 @@ protected boolean isHidingTopControlsEnabled() {
                 !AccessibilityUtil.isAccessibilityEnabled(getApplicationContext());
         enableHidingTopControls &= !mIsImeShowing;
         enableHidingTopControls &= !mIsShowingErrorPage;
+        enableHidingTopControls &= !getWebContents().isShowingInterstitialPage();
 
         return enableHidingTopControls;
     }

chrome/browser/android/tab_android.cc

@@ -59,10 +59,12 @@
 #include "components/url_fixer/url_fixer.h"
 #include "content/public/browser/android/content_view_core.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/interstitial_page.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_view_host.h"
 #include "content/public/browser/user_metrics.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/top_controls_state.h"
@@ -737,6 +739,14 @@ void TabAndroid::UpdateTopControlsState(JNIEnv* env,
   WebContents* sender = web_contents();
   sender->Send(new ChromeViewMsg_UpdateTopControlsState(
       sender->GetRoutingID(), constraints_state, current_state, animate));
+
+  if (sender->ShowingInterstitialPage()) {
+    content::RenderViewHost* interstitial_view_host =
+        sender->GetInterstitialPage()->GetMainFrame()->GetRenderViewHost();
+    interstitial_view_host->Send(new ChromeViewMsg_UpdateTopControlsState(
+        interstitial_view_host->GetRoutingID(), constraints_state,
+        current_state, animate));
+  }
 }
 
 void TabAndroid::SearchByImageInNewTabAsync(JNIEnv* env, jobject obj) {