Print less output from compare_videos.py in WebRTC quality test.

chrome/browser/media/chrome_webrtc_video_quality_browsertest.cc

 // Copyright 2013 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 "base/environment.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
 #include "base/strings/string_split.h"
 #include "base/strings/stringprintf.h"
@@ skipping 265 matching lines @@
     compare_command.AppendArg("--yuv_frame_width");
     compare_command.AppendArg(base::StringPrintf("%d", width));
     compare_command.AppendArg("--yuv_frame_height");
     compare_command.AppendArg(base::StringPrintf("%d", height));
     compare_command.AppendArg("--stats_file");
     compare_command.AppendArgPath(stats_file);
 
     VLOG(0) << "Running " << compare_command.GetCommandLineString();
     std::string output;
     bool ok = base::GetAppOutput(compare_command, &output);
+
+    size_t first_result_line_pos = output.find("RESULT");
+    if (first_result_line_pos == std::string::npos) {
+      LOG(ERROR) << "Got unexpected output from compare_videos.py:"
+                 << output;
+      return false;
+    }
+
     // Print to stdout to ensure the perf numbers are parsed properly by the
-    // buildbot step.
-    printf("Output was:\n\n%s\n", output.c_str());
+    // buildbot step. Only print the result lines to ensure we write all of
+    // it before we hit some os buffer limit and give other processes the
+    // chance to write to Chrome's stdout.
+    std::string result_lines = output.substr(first_result_line_pos);
+    printf("Output was:\n\n%s\n", result_lines.c_str());
     return ok;
   }
 
   base::FilePath GetWorkingDir() {
     std::string home_dir;
     environment_->GetVar(kHomeEnvName, &home_dir);
     base::FilePath::StringType native_home_dir(home_dir.begin(),
                                                home_dir.end());
     return base::FilePath(native_home_dir).Append(kWorkingDirName);
   }
@@ skipping 67 matching lines @@
 
   RunARGBtoI420Converter(
       kVgaWidth, kVgaHeight, GetWorkingDir().Append(kCapturedYuvFileName));
   ASSERT_TRUE(
       CompareVideosAndPrintResult(kVgaWidth,
                                   kVgaHeight,
                                   GetWorkingDir().Append(kCapturedYuvFileName),
                                   GetWorkingDir().Append(kReferenceYuvFileName),
                                   GetWorkingDir().Append(kStatsFileName)));
 }