Rework UMAHistogramHelper and StatisticsDeltaReader into [Chrome]HistogramTester.

content/public/test/browser_test_utils.cc

 // Copyright (c) 2012 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.
 
 #include "content/public/test/browser_test_utils.h"
 
+#include "base/bind.h"
 #include "base/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/path_service.h"
 #include "base/process/kill.h"
 #include "base/rand_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/test/test_timeouts.h"
 #include "base/values.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/web_contents/web_contents_view.h"
 #include "content/common/input/synthetic_web_input_event_builders.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/dom_operation_notification_details.h"
+#include "content/public/browser/histogram_fetcher.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/test/test_utils.h"
 #include "grit/webui_resources.h"
 #include "net/base/filename_util.h"
@@ skipping 555 matching lines @@
       browser_context->GetRequestContext();
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&SetCookieOnIOThread, url, value,
                  make_scoped_refptr(context_getter), &event, &result));
   event.Wait();
   return result;
 }
 
+void FetchHistogramsFromChildProcesses() {
+  scoped_refptr<content::MessageLoopRunner> runner = new MessageLoopRunner;
+
+  FetchHistogramsAsynchronously(
+      base::MessageLoop::current(),
+      runner->QuitClosure(),
+      // If this call times out, it means that a child process is not
+      // responding, which is something we should not ignore.  The timeout is
+      // set to be longer than the normal browser test timeout so that it will
+      // be prempted by the normal timeout.
+      TestTimeouts::action_max_timeout() * 2);

[Paweł Hajdan Jr., 2014/07/23 10:50:58]

The timeouts returned by TestTimeout should not be multiplied.

There must be some better solution than this.

[Ilya Sherman, 2014/07/23 17:25:11]

What is your objection to multiplying the timeout?  The goal is to have the test
time out if the FetchHistogramsAsynchronously call fails (also with a timeout). 
The multiplication isn't strictly necessary, I suppose; using
action_max_timeout() directly should, in theory, given the same result.

[brettw, 2014/08/04 05:45:49]

I agree with Pawel. We shouldn't have arbitrary timeouts unless there is some
specific justification. Using action_max_timeout directly should be sufficient.
If this isn't long enough, we have a different problem.

+  runner->Run();
+}
+
 TitleWatcher::TitleWatcher(WebContents* web_contents,
                            const base::string16& expected_title)
     : WebContentsObserver(web_contents),
       message_loop_runner_(new MessageLoopRunner) {
   EXPECT_TRUE(web_contents != NULL);
   expected_titles_.push_back(expected_title);
 }
 
 void TitleWatcher::AlsoWaitForTitle(const base::string16& expected_title) {
   expected_titles_.push_back(expected_title);
@@ skipping 120 matching lines @@
   }
   // The queue should not be empty, unless we were quit because of a timeout.
   if (message_queue_.empty())
     return false;
   *message = message_queue_.front();
   message_queue_.pop();
   return true;
 }
 
 }  // namespace content