aw: Change telemetry traces to collect better startup time stats.

1) Time new WebView + setContentView - this tests how an app that
   has a WebView in its layout will be affected.
2) Time the full time from new WebView to onPageFinished. This
   allows us to know if we regress something that happens
   asynchronously on startup that blocks URL loading.

BUG=

Review-Url: https://codereview.chromium.org/2380053002
Cr-Commit-Position: refs/heads/master@{#422798}

android_webview/tools/system_webview_shell/apk/src/org/chromium/webview_shell/TelemetryActivity.java

@@ -18,6 +18,8 @@ import android.webkit.WebViewClient;
 public class TelemetryActivity extends Activity {
     static final String DEFAULT_START_UP_TRACE_TAG = "WebViewStartupInterval";
     static final String DEFAULT_LOAD_URL_TRACE_TAG = "WebViewBlankUrlLoadInterval";
+    static final String DEFAULT_START_UP_AND_LOAD_URL_TRACE_TAG =
+            "WebViewStartupAndLoadBlankUrlInterval";
 
     @Override
     public void onCreate(Bundle savedInstanceState) {
@@ -28,11 +30,15 @@ public class TelemetryActivity extends Activity {
         Intent intent = getIntent();
         final String startUpTraceTag = intent.getStringExtra("WebViewStartUpTraceTag");
         final String loadUrlTraceTag = intent.getStringExtra("WebViewLoadUrlTraceTag");
+        final String startUpAndLoadUrlTraceTag =
+                intent.getStringExtra("WebViewStartUpAndLoadUrlTraceTag");
 
+        Trace.beginSection(startUpTraceTag == null ? DEFAULT_START_UP_AND_LOAD_URL_TRACE_TAG
+                                                   : startUpAndLoadUrlTraceTag);
         Trace.beginSection(startUpTraceTag == null ? DEFAULT_START_UP_TRACE_TAG : startUpTraceTag);
         WebView webView = new WebView(this);
-        Trace.endSection();
         setContentView(webView);
+        Trace.endSection();
 
         CookieManager.setAcceptFileSchemeCookies(true);
         WebSettings settings = webView.getSettings();
@@ -56,6 +62,7 @@ public class TelemetryActivity extends Activity {
                 public void onPageFinished(WebView view, String url) {
                     super.onPageFinished(view, url);
                     Trace.endSection();
+                    Trace.endSection();
                 }
         });