Change uses of base::JoinString to pass StringPieces where possible.

content/browser/gpu/gpu_data_manager_impl_private.cc

 // Copyright (c) 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 "content/browser/gpu/gpu_data_manager_impl_private.h"
 
 #include <algorithm>
 #include <iterator>
 #include <memory>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
 #include "base/version.h"
 #include "build/build_config.h"
 #include "cc/base/switches.h"
 #include "content/browser/gpu/gpu_process_host.h"
 #include "content/common/gpu_host_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/gpu_data_manager_observer.h"
@@ skipping 624 matching lines @@
 
   if (gpu_blacklist_) {
     std::set<int> features = gpu_blacklist_->MakeDecision(
         gpu::GpuControlList::kOsAny, os_version, gpu_info_);
     if (update_histograms_)
       UpdateStats(gpu_info_, gpu_blacklist_.get(), features);
 
     UpdateBlacklistedFeatures(features);
   }
 
-  std::set<std::string> disabled_ext_set;
+  std::string command_line_disable_gl_extensions;
+  std::vector<std::string> disabled_driver_bug_exts;
+  // Holds references to strings in the above two variables.
+  std::set<base::StringPiece> disabled_ext_set;
 
   // Merge disabled extensions from the command line with gpu driver bug list.
   if (command_line) {
-    const std::vector<std::string>& disabled_command_line_exts =
-        base::SplitString(
-            command_line->GetSwitchValueASCII(switches::kDisableGLExtensions),
-            ", ;", base::KEEP_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+    command_line_disable_gl_extensions =
+        command_line->GetSwitchValueASCII(switches::kDisableGLExtensions);
+    std::vector<base::StringPiece> disabled_command_line_exts =
+        base::SplitStringPiece(command_line_disable_gl_extensions, ", ;",
+                               base::KEEP_WHITESPACE,
+                               base::SPLIT_WANT_NONEMPTY);
     disabled_ext_set.insert(disabled_command_line_exts.begin(),
                             disabled_command_line_exts.end());
   }
 
   if (gpu_driver_bug_list_) {
     gpu_driver_bugs_ = gpu_driver_bug_list_->MakeDecision(
         gpu::GpuControlList::kOsAny, os_version, gpu_info_);
 
-    const std::vector<std::string>& disabled_driver_bug_exts =
-        gpu_driver_bug_list_->GetDisabledExtensions();
+    disabled_driver_bug_exts = gpu_driver_bug_list_->GetDisabledExtensions();
     disabled_ext_set.insert(disabled_driver_bug_exts.begin(),
                             disabled_driver_bug_exts.end());
   }
   disabled_extensions_ =
-      base::JoinString(std::vector<std::string>(disabled_ext_set.begin(),
-                                                disabled_ext_set.end()),
+      base::JoinString(std::vector<base::StringPiece>(disabled_ext_set.begin(),
+                                                      disabled_ext_set.end()),
                        " ");
 
   gpu::GpuDriverBugList::AppendWorkaroundsFromCommandLine(
       &gpu_driver_bugs_, *base::CommandLine::ForCurrentProcess());
 
   // We have to update GpuFeatureType before notify all the observers.
   NotifyGpuInfoUpdate();
 }
 
 void GpuDataManagerImplPrivate::UpdateGpuInfo(const gpu::GPUInfo& gpu_info) {
@@ skipping 682 matching lines @@
   gpu_info_.context_info_state = gpu::kCollectInfoFatalFailure;
 #if defined(OS_WIN)
   gpu_info_.dx_diagnostics_info_state = gpu::kCollectInfoFatalFailure;
 #endif
   complete_gpu_info_already_requested_ = true;
   // Some observers might be waiting.
   NotifyGpuInfoUpdate();
 }
 
 }  // namespace content