[Chromeshine] Attach PageViewObserver for WebAppActivity

Bug: 996947
Change-Id: Ic5d588456dd807e7658557d66e3bf4670b11b16c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1766457Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Commit-Queue: Patrick Noland <pnoland@chromium.org>
Cr-Commit-Position: refs/heads/master@{#690065}

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java

@@ -50,6 +50,7 @@ import org.chromium.chrome.browser.tab.TabObserver;
 import org.chromium.chrome.browser.tab.TabObserverRegistrar;
 import org.chromium.chrome.browser.tab.TabState;
 import org.chromium.chrome.browser.toolbar.top.ToolbarControlContainer;
+import org.chromium.chrome.browser.usage_stats.UsageStatsService;
 import org.chromium.chrome.browser.util.ColorUtils;
 import org.chromium.chrome.browser.widget.TintedDrawable;
 import org.chromium.content_public.browser.LoadUrlParams;
@@ -335,6 +336,10 @@ public class WebappActivity extends SingleTabActivity {
         getToolbarManager().setShowTitle(true);
         getToolbarManager().setCloseButtonDrawable(null); // Hides close button.
 
+        if (UsageStatsService.isEnabled() && !mWebappInfo.isSplashProvidedByWebApk()) {
+            UsageStatsService.getInstance().createPageViewObserver(getTabModelSelector(), this);
+        }
+
         getFullscreenManager().setTab(getActivityTab());
         super.finishNativeInitialization();
         mIsInitialized = true;