Expose swapping the web contents out to observers

BUG=321901

Review URL: https://codereview.chromium.org/89563002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238874 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 11 insertions, 0 deletions

diff --git a/chrome/android/java/src/org/chromium/chrome/browser/EmptyTabObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/EmptyTabObserver.java
index aecf9cf..d812f16 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/EmptyTabObserver.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/EmptyTabObserver.java
@@ -19,6 +19,9 @@ public class EmptyTabObserver implements TabObserver {
     public void onFaviconUpdated(TabBase tab) { }
 
     @Override
+    public void onWebContentsSwapped(TabBase tab) { }
+
+    @Override
     public void onLoadProgressChanged(TabBase tab, int progress) { }
 
     @Override
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java b/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
index f809409..05f1386 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/TabBase.java
@@ -713,6 +713,7 @@ public abstract class TabBase implements NavigationClient {
         mContentViewCore.attachImeAdapter();
         for (TabObserver observer : mObservers) observer.onContentChanged(this);
         destroyNativePageInternal(previousNativePage);
+        for (TabObserver observer : mObservers) observer.onWebContentsSwapped(this);
     }
 
     @CalledByNative
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java
index c967cc5..78f963d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java
@@ -27,6 +27,12 @@ public interface TabObserver {
      */
     void onFaviconUpdated(TabBase tab);
 
+    /**
+     * Called when the WebContents of a {@link TabBase} have been swapped.
+     * @param tab The notifying {@link TabBase}.
+     */
+    void onWebContentsSwapped(TabBase tab);
+
     // WebContentsDelegateAndroid methods ---------------------------------------------------------
 
     /**
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 16b9ebe..c0f2341 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -2871,6 +2871,7 @@ public class ContentViewCore
      * once the texture is actually ready.
      */
     public boolean isReady() {
+        if (mNativeContentViewCore == 0) return false;
         return nativeIsRenderWidgetHostViewReady(mNativeContentViewCore);
     }