[WebView] Add a new flushVisualState API to AwContents.

android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java

Index: android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java
diff --git a/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java b/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java
index fbba821a7ced05b9885da13e305a8441deac84e9..4a900f27d9da31fb5cd1ac4ffb6496a9f52ed3cf 100644
--- a/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java
+++ b/android_webview/javatests/src/org/chromium/android_webview/test/AwContentsTest.java
@@ -7,6 +7,7 @@ package org.chromium.android_webview.test;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Canvas;
+import android.graphics.Color;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
@@ -20,6 +21,7 @@ import android.view.View;
 import org.apache.http.Header;
 import org.apache.http.HttpRequest;
 import org.chromium.android_webview.AwContents;
+import org.chromium.android_webview.AwContents.VisualStateFlushCallback;
 import org.chromium.android_webview.AwSettings;
 import org.chromium.android_webview.test.TestAwContentsClient.OnDownloadStartHelper;
 import org.chromium.android_webview.test.util.CommonResources;
@@ -35,9 +37,11 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * AwContents tests.
@@ -562,4 +566,156 @@ public class AwContentsTest extends AwTestBase {
         loadUrlSync(awContents, mContentsClient.getOnPageFinishedHelper(), pageUrl);
         assertEquals(onSslErrorCallCount + 1, onReceivedSslErrorHelper.getCallCount());
     }
+
+    @Feature({"AndroidWebView"})
+    @SmallTest
+    public void testFlushVisualState() throws Throwable {
+        AwTestContainerView testContainer =
+                createAwTestContainerViewOnMainSync(mContentsClient);
+        final AwContents awContents = testContainer.getAwContents();
+        loadUrlSync(awContents,
+                mContentsClient.getOnPageFinishedHelper(), CommonResources.ABOUT_HTML);
+        final CallbackHelper ch = new CallbackHelper();
+        final int chCount = ch.getCallCount();
+        runTestOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                awContents.flushVisualState(new AwContents.VisualStateFlushCallback() {
+                    @Override
+                    public void onComplete() {
+                        ch.notifyCalled();
+                    }
+
+                    @Override
+                    public void onFailure(int reason) {}
+                });
+            }
+        });
+        ch.waitForCallback(chCount);
+    }
+
+    @Feature({"AndroidWebView"})
+    @SmallTest
+    public void testLoadBlankDrawsBackgroundImmediately() throws Throwable {
+        // This test loads a page with a blue background color. It then waits until this page
+        // is drawn and then calls loadBlank and checks that the background color of the view
+        // (in this case red) is drawn immediately instead of the contents of the blue page.
+        final CountDownLatch bluePageDrawnSignal = new CountDownLatch(1);
+        final LoadUrlParams bluePageUrl = createTestPageUrl("blue");
+
+        final AtomicReference<AwContents> awContentsRef = new AtomicReference<>();
+        final AwTestContainerView testView = createAwTestContainerViewOnMainSync(
+                new TestAwContentsClient() {
+                    @Override
+                    public void onPageFinished(String url) {
+                        if (bluePageUrl.getUrl().equals(url)) {
+                            // We flush from onPageFinished to ensure that the blue page contents
+                            // have been drawn when the flush callback is received.
+                            awContentsRef.get().flushVisualState(
+                                    createFlushCallback(bluePageDrawnSignal));
+                        }
+                    }
+                });
+        final AwContents awContents = testView.getAwContents();
+        awContentsRef.set(awContents);
+
+        getInstrumentation().runOnMainSync(new Runnable() {
+            @Override
+            public void run() {
+                awContents.setBackgroundColor(Color.RED);
+                awContents.loadUrl(bluePageUrl);
+            }
+        });
+
+        bluePageDrawnSignal.await();
+
+        getInstrumentation().runOnMainSync(new Runnable() {
+            @Override
+            public void run() {
+                Bitmap blueBitmap = drawIntoBitmap(awContents);
+                assertEquals(Color.BLUE, blueBitmap.getPixel(0, 0));
+
+                // Check that the background color is drawn immediately after loading blank.
+                // Note that we don't need to wait for any events such as onPageFinished.
+                awContents.loadBlank();
+                Bitmap redBitmap = drawIntoBitmap(awContents);
+                assertEquals(Color.RED, redBitmap.getPixel(0, 0));
+            }
+        });
+    }
+
+    @Feature({"AndroidWebView"})
+    @SmallTest
+    public void testLoadBlankDoesNotBlockSubsequentLoads() throws Throwable {
+        // This test briefly loads a yellow page and then immediately calls loadBlank which should
+        // draw the background color of the view immediately (in this case red). It then tries to
+        // load a page with blue background and waits until this page is drawn.
+        final CountDownLatch bluePageDrawnSignal = new CountDownLatch(1);
+        final LoadUrlParams bluePageUrl = createTestPageUrl("blue");
+
+        final AtomicReference<AwContents> awContentsRef = new AtomicReference<>();
+        final AwTestContainerView testView = createAwTestContainerViewOnMainSync(
+                new TestAwContentsClient() {
+                    @Override
+                    public void onPageFinished(String url) {
+                        if (bluePageUrl.getUrl().equals(url)) {
+                            awContentsRef.get().flushVisualState(
+                                    createFlushCallback(bluePageDrawnSignal));
+                        }
+                    }
+                });
+        final AwContents awContents = testView.getAwContents();
+        awContentsRef.set(awContents);
+
+        getInstrumentation().runOnMainSync(new Runnable() {
+            @Override
+            public void run() {
+                awContents.loadUrl(createTestPageUrl("yellow"));
+                awContents.setBackgroundColor(Color.RED);
+                awContents.loadBlank();
+                Bitmap redBitmap = drawIntoBitmap(awContents);
+                assertEquals(Color.RED, redBitmap.getPixel(0, 0));
+
+                // Loading blank previously should not block this load.
+                awContents.loadUrl(bluePageUrl);
+            }
+        });
+
+        bluePageDrawnSignal.await();
+
+        getInstrumentation().runOnMainSync(new Runnable() {
+            @Override
+            public void run() {
+                Bitmap blueBitmap = drawIntoBitmap(awContents);
+                assertEquals(Color.BLUE, blueBitmap.getPixel(0, 0));
+            }
+        });
+    }
+
+    private static VisualStateFlushCallback createFlushCallback(final CountDownLatch latch) {
+        return new VisualStateFlushCallback() {
+            @Override
+            public void onFailure(int reason) {
+                fail("onFailure received");
+            }
+
+            @Override
+            public void onComplete() {
+                latch.countDown();
+            }
+        };
+    }
+
+    private static final LoadUrlParams createTestPageUrl(String backgroundColor) {
+        return LoadUrlParams.createLoadDataParams(
+                "<html><body bgcolor=" + backgroundColor + "></body></html>",
+                "text/html", false);
+    }
+
+    private Bitmap drawIntoBitmap(AwContents awContents) {
+        Bitmap bitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);
+        Canvas canvas = new Canvas(bitmap);
+        awContents.onDraw(canvas);
+        return bitmap;
+    }
 }