Reland "[WebLayer] Fix crash when top controls view has 0 height"

This is a reland of e26a5125

This conflicted with http://crrev.com/c/1888389 and caused a compile error.

Original change's description:
> [WebLayer] Fix crash when top controls view has 0 height
>
> This happens because the adapter and layer for the top controls is only
> created once height and width are > 0. We were assuming this had already
> been created in setTopControlsOffset().
>
> Change-Id: Idf104f9d5c951c1fa8719fa30661dceae59b4887
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890492
> Commit-Queue: Clark DuVall <cduvall@chromium.org>
> Reviewed-by: Scott Violet <sky@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#710897}

TBR=sky@chromium.org

Change-Id: I482a241fcb43fe2bff3ec8f315cfed5ee266e828
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890959Reviewed-by: Clark DuVall <cduvall@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711013}

weblayer/browser/top_controls_container_view.cc

@@ -71,8 +71,10 @@ void TopControlsContainerView::SetTopControlsOffset(
     const base::android::JavaParamRef<jobject>& caller,
     int top_controls_offset_y,
     int top_content_offset_y) {
-  DCHECK(top_controls_layer_);
-  top_controls_layer_->SetPosition(gfx::PointF(0, top_controls_offset_y));
+  // |top_controls_layer_| may not be created if the top controls view has 0
+  // height.
+  if (top_controls_layer_)
+    top_controls_layer_->SetPosition(gfx::PointF(0, top_controls_offset_y));
   web_contents()->GetNativeView()->GetLayer()->SetPosition(
       gfx::PointF(0, top_content_offset_y));
 }

weblayer/shell/android/javatests/src/org/chromium/weblayer/test/InstrumentationActivityTestRule.java

@@ -131,7 +131,11 @@ public class InstrumentationActivityTestRule extends ActivityTestRule<Instrument
      * Loads the given URL in the shell.
      */
     public void navigateAndWait(String url) {
-        NavigationWaiter waiter = new NavigationWaiter(url, getActivity().getBrowserController());
+        navigateAndWait(getActivity().getBrowserController(), url);
+    }
+
+    public void navigateAndWait(BrowserController controller, String url) {
+        NavigationWaiter waiter = new NavigationWaiter(url, controller);
         waiter.navigateAndWait();
     }
 

weblayer/shell/android/javatests/src/org/chromium/weblayer/test/TopControlsTest.java

@@ -5,20 +5,24 @@
 package org.chromium.weblayer.test;
 
 import android.support.test.filters.SmallTest;
+import android.support.v4.app.Fragment;
 import android.view.View;
+import android.widget.FrameLayout;
 
-import org.json.JSONObject;
 import org.junit.Assert;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
 import org.chromium.base.test.BaseJUnit4ClassRunner;
+import org.chromium.base.test.util.CallbackHelper;
 import org.chromium.base.test.util.UrlUtils;
 import org.chromium.content_public.browser.test.util.Criteria;
 import org.chromium.content_public.browser.test.util.CriteriaHelper;
 import org.chromium.content_public.browser.test.util.TestThreadUtils;
 import org.chromium.weblayer.BrowserController;
+import org.chromium.weblayer.BrowserFragmentController;
+import org.chromium.weblayer.WebLayer;
 import org.chromium.weblayer.shell.InstrumentationActivity;
 
 /**
@@ -32,18 +36,43 @@ public class TopControlsTest {
 
     private int mTopControlsHeight;
     private int mInitialVisiblePageHeight;
+    private BrowserController mBrowserController;
+    private BrowserFragmentController mBrowserFragmentController;
 
     /**
      * Returns the visible height of the page as determined by JS. The returned value is in CSS
      * pixels (which are most likely not the same as device pixels).
      */
     private int getVisiblePageHeight() {
-        try {
-            JSONObject result = mActivityTestRule.executeScriptSync("window.innerHeight");
-            return result.getInt(BrowserController.SCRIPT_RESULT_KEY);
-        } catch (Exception e) {
-            return -1;
-        }
+        return mActivityTestRule.executeScriptAndExtractInt("window.innerHeight");
+    }
+
+    @Test
+    @SmallTest
+    public void testZeroHeight() throws Exception {
+        InstrumentationActivity activity = mActivityTestRule.launchShellWithUrl(null);
+        TestThreadUtils.runOnUiThreadBlocking(() -> {
+            Fragment fragment = WebLayer.createBrowserFragment(null);
+            activity.getSupportFragmentManager()
+                    .beginTransaction()
+                    .add(android.R.id.content, fragment)
+                    .commitNow();
+            mBrowserFragmentController = BrowserFragmentController.fromFragment(fragment);
+            mBrowserFragmentController.setTopView(new FrameLayout(activity));
+            mBrowserController = mBrowserFragmentController.getBrowserController();
+        });
+
+        mActivityTestRule.navigateAndWait(
+                mBrowserController, UrlUtils.encodeHtmlDataUri("<html></html>"));
+
+        // Calling setSupportsEmbedding() makes sure onTopControlsChanged() will get called, which
+        // should not crash.
+        CallbackHelper helper = new CallbackHelper();
+        TestThreadUtils.runOnUiThreadBlocking(() -> {
+            mBrowserFragmentController.setSupportsEmbedding(true).addCallback(
+                    (Boolean result) -> { helper.notifyCalled(); });
+        });
+        helper.waitForCallback(0);
     }
 
     @Test