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

ui/gl/gl_implementation.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 "ui/gl/gl_implementation.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <string>
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "build/build_config.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_gl_api_implementation.h"
 #include "ui/gl/gl_version_info.h"
 
 namespace gl {
 
 namespace {
@@ skipping 128 matching lines @@
 bool HasInitializedNullDrawGLBindings() {
   return GetNullDrawBindingsEnabled();
 }
 
 std::string FilterGLExtensionList(
     const char* extensions,
     const std::vector<std::string>& disabled_extensions) {
   if (extensions == NULL)
     return "";
 
-  std::vector<std::string> extension_vec = base::SplitString(
+  std::vector<base::StringPiece> extension_vec = base::SplitStringPiece(
       extensions, " ", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
 
-  auto is_disabled = [&disabled_extensions](const std::string& ext) {
+  auto is_disabled = [&disabled_extensions](const base::StringPiece& ext) {
     return std::find(disabled_extensions.begin(), disabled_extensions.end(),
                      ext) != disabled_extensions.end();
   };
   extension_vec.erase(
       std::remove_if(extension_vec.begin(), extension_vec.end(), is_disabled),
       extension_vec.end());
 
   return base::JoinString(extension_vec, " ");
 }
 
@@ skipping 15 matching lines @@
 std::string GetGLExtensionsFromCurrentContext(GLApi* api) {
   if (WillUseGLGetStringForExtensions(api)) {
     const char* extensions =
         reinterpret_cast<const char*>(api->glGetStringFn(GL_EXTENSIONS));
     return extensions ? std::string(extensions) : std::string();
   }
 
   GLint num_extensions = 0;
   api->glGetIntegervFn(GL_NUM_EXTENSIONS, &num_extensions);
 
-  std::vector<std::string> exts(num_extensions);
+  std::vector<base::StringPiece> exts(num_extensions);
   for (GLint i = 0; i < num_extensions; ++i) {
     const char* extension =
         reinterpret_cast<const char*>(api->glGetStringiFn(GL_EXTENSIONS, i));
     DCHECK(extension != NULL);
     exts[i] = extension;
   }
   return base::JoinString(exts, " ");
 }
 
 bool WillUseGLGetStringForExtensions() {
@@ skipping 28 matching lines @@
   base::NativeLibrary library = base::LoadNativeLibrary(filename, &error);
   if (!library) {
     LOG(ERROR) << "Failed to load " << filename.MaybeAsASCII() << ": "
                << error.ToString();
     return NULL;
   }
   return library;
 }
 
 }  // namespace gl