customtabs: UMA histogram tracking whether clients call warmup().

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.customtabs;
 
 import android.app.ActivityManager;
 import android.app.Application;
 import android.content.Context;
 import android.content.Intent;
@@ skipping 114 matching lines @@
                 cancelPrerender(session);
             }
         };
         return mClientManager.newSession(callback, Binder.getCallingUid(), onDisconnect);
     }
 
     @Override
     public boolean warmup(long flags) {
         // Here and in mayLaunchUrl(), don't do expensive work for background applications.
         if (!isCallerForegroundOrSelf()) return false;
+        mClientManager.recordUidHasCalledWarmup(Binder.getCallingUid());
         if (!mWarmupHasBeenCalled.compareAndSet(false, true)) return true;
         // The call is non-blocking and this must execute on the UI thread, post a task.
         ThreadUtils.postOnUiThread(new Runnable() {
             @Override
             @SuppressFBWarnings("DM_EXIT")
             public void run() {
                 ChromeApplication app = (ChromeApplication) mApplication;
                 try {
                     app.startBrowserProcessesAndLoadLibrariesSync(true);
                 } catch (ProcessInitException e) {
@@ skipping 378 matching lines @@
         screenSize.x /= density;
         screenSize.y /= density;
         return screenSize;
     }
 
     @VisibleForTesting
     void resetThrottling(Context context, int uid) {
         mClientManager.resetThrottling(uid);
     }
 }