[aw] Fix screen portion percentage cast error

When passing the screen coverage percentage to
AwContentsJni#updateOpenWebScreenArea(), a float value was cast to an int,
which always produced zero. This change multiplies the float value by 100
to match the expectation for an integer percentage and adds a test that
verifies that the screen portion histogram contains samples for a
non-zero percentage bucket.

Bug: 1122091
Change-Id: I592b2a72d6ceb80108d9dfe73d25d55164709a5a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2924108
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Reviewed-by: Peter Conn <peconn@chromium.org>
Commit-Queue: Oksana Zhuravlova <oksamyt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#893127}

android_webview/java/src/org/chromium/android_webview/AwContents.java

@@ -932,7 +932,7 @@ private void recalculate() {
                     (float) openWebPixelCoverage / RectUtils.getRectArea(rootVisibleRect);
 
             AwContentsJni.get().updateOpenWebScreenArea(
-                    openWebPixelCoverage, (int) openWebVisiblePercentage);
+                    openWebPixelCoverage, (int) (openWebVisiblePercentage * 100));
         }
     }
 

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

@@ -19,6 +19,7 @@
 
 import org.chromium.android_webview.AwBrowserProcess;
 import org.chromium.android_webview.AwContents;
+import org.chromium.android_webview.common.AwFeatures;
 import org.chromium.android_webview.common.PlatformServiceBridge;
 import org.chromium.android_webview.metrics.AwMetricsServiceClient;
 import org.chromium.base.Callback;
@@ -401,4 +402,32 @@ public void testRendererHistograms() throws Throwable {
             embeddedTestServer.stopAndDestroyServer();
         }
     }
+
+    @Test
+    @MediumTest
+    @Feature({"AndroidWebView"})
+    @CommandLineFlags.Add({"enable-features=" + AwFeatures.WEBVIEW_MEASURE_SCREEN_COVERAGE})
+    public void testScreenCoverageReporting() throws Throwable {
+        EmbeddedTestServer embeddedTestServer = EmbeddedTestServer.createAndStartServer(
+                InstrumentationRegistry.getInstrumentation().getContext());
+        try {
+            mRule.loadUrlAsync(mAwContents,
+                    embeddedTestServer.getURL("/android_webview/test/data/hello_world.html"));
+
+            // We need to wait for log collection because the histogram is recorded during
+            // MetricsProvider::ProvideCurrentSessionData().
+            mPlatformServiceBridge.waitForNextMetricsLog();
+
+            final String histogramName = "Android.WebView.WebViewOpenWebVisible.ScreenPortion";
+            int totalSamples = RecordHistogram.getHistogramTotalCountForTesting(histogramName);
+            Assert.assertNotEquals("There should be at least one sample recorded", 0, totalSamples);
+
+            int zeroBucketSamples =
+                    RecordHistogram.getHistogramValueCountForTesting(histogramName, 0);
+            Assert.assertNotEquals("There should be at least one sample in a non-zero bucket",
+                    zeroBucketSamples, totalSamples);
+        } finally {
+            embeddedTestServer.stopAndDestroyServer();
+        }
+    }
 }