PrintPreviewPdfGeneratedBrowserTest properly listens to messages and exits correctly.

chrome/browser/printing/print_preview_pdf_generated_browsertest.cc

 // Copyright 2014 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 <algorithm>
 #include <fstream>
 #include <iostream>
 #include <iterator>
 #include <limits>
 #include <string>
@@ skipping 626 matching lines @@
   //
   // Throughout this code, there will be |std::cout| statements. The layout test
   // framework uses stdout to get data from the browser test and uses stdin
   // to send data to the browser test. Writing "EOF\n" to |std::cout| indicates
   // that whatever block of data that the test was expecting has been completely
   // sent. Sometimes EOF is printed to stderr because the test will expect it
   // from stderr in addition to stdout for certain blocks of data.
   InitPdfFunctions();
   SetupStdinAndSavePath();
 
-  // There is no way to determine how many tests are to be run ahead of time
-  // without undesirable changes to the layout test framework. However, that is
-  // ok since whenever all the tests have been run, the layout test framework
-  // calls SIGKILL on this process, ending the test. This will end the while
-  // loop and cause the test to clean up after itself. For this to work, the
-  // browsertest must be run with '--single_process' not '--single-process.'
   while (true) {
     std::string input;
-    std::getline(std::cin, input);
-    if (input.empty()) {
-      while (std::cin.eof()) {
+    while (input.empty()) {
+      std::getline(std::cin, input);
+      if (std::cin.eof())
         std::cin.clear();
-        std::getline(std::cin, input);
-        if (!input.empty()) {
-          break;
-        }
-      }
     }
 
+    // If the layout test framework sends "QUIT" to this test, that means there
+    // are no more tests for this instance to run and it should quit.
+    if (input == "QUIT")
+      break;
+
     base::FilePath::StringType file_extension = FILE_PATH_LITERAL(".pdf");
     base::FilePath::StringType cmd;
 #if defined(OS_POSIX)
     cmd = input;
 #elif defined(OS_WIN)
     cmd = base::UTF8ToWide(input);
 #endif
 
     DuplicateTab();
     PrintPreviewSettings settings(
@@ skipping 22 matching lines @@
     // waiting for this message and start waiting for the image data.
     std::cout << "#EOF\n";
     std::cout.flush();
 
     SendPng();
     Reset();
   }
 }
 
 }  // namespace printing