Fix main intent metrics when zero tabs present.

The previous ignore logic was incorrect as it was both calling
create and set index.  Thus the zero tabs case was resulting in
switch tabs always.

Adds tests to catch regressions going forward.

BUG=717062

Review-Url: https://codereview.chromium.org/2850163002
Cr-Commit-Position: refs/heads/master@{#468493}
diff --git a/chrome/android/java_sources.gni b/chrome/android/java_sources.gni
index e5124e3..ac81236 100644
--- a/chrome/android/java_sources.gni
+++ b/chrome/android/java_sources.gni
@@ -1428,6 +1428,7 @@
   "javatests/src/org/chromium/chrome/browser/media/router/MockMediaRouteProvider.java",
   "javatests/src/org/chromium/chrome/browser/media/ui/AutoplayMutedNotificationTest.java",
   "javatests/src/org/chromium/chrome/browser/media/ui/PauseOnHeadsetUnplugTest.java",
+  "javatests/src/org/chromium/chrome/browser/metrics/MainIntentBehaviorMetricsIntegrationTest.java",
   "javatests/src/org/chromium/chrome/browser/metrics/PageLoadMetricsTest.java",
   "javatests/src/org/chromium/chrome/browser/multiwindow/MultiWindowIntegrationTest.java",
   "javatests/src/org/chromium/chrome/browser/multiwindow/MultiWindowUtilsTest.java",