Cleanup: Pass std::string as const reference if possible

gpu/tools/compositor_model_bench/shaders.cc

 // Copyright (c) 2011 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 "gpu/tools/compositor_model_bench/shaders.h"
 
 #include <algorithm>
 
 #include "gpu/tools/compositor_model_bench/render_model_utils.h"
 #include "gpu/tools/compositor_model_bench/render_tree.h"
@@ skipping 63 matching lines @@
 }
 
 static void TranslateInPlace(float* m, float tx, float ty, float tz) {
   m[12] += tx;
   m[13] += ty;
   m[14] += tz;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
-ShaderID ShaderIDFromString(std::string name) {
+ShaderID ShaderIDFromString(const std::string& name) {
   if (name == "VertexShaderPosTexYUVStretch")
     return VERTEX_SHADER_POS_TEX_YUV_STRETCH;
   if (name == "VertexShaderPosTex")
     return VERTEX_SHADER_POS_TEX;
   if (name == "VertexShaderPosTexTransform")
     return VERTEX_SHADER_POS_TEX_TRANSFORM;
   if (name == "FragmentShaderYUVVideo")
     return FRAGMENT_SHADER_YUV_VIDEO;
   if (name == "FragmentShaderRGBATexFlipAlpha")
     return FRAGMENT_SHADER_RGBA_TEX_FLIP_ALPHA;
@@ skipping 346 matching lines @@
   float center_y = (top+bottom)/2 - g_current_tile_layer_height/2;
   TranslateInPlace(mv_transform, center_x, center_y, 0.0);
 
   Project(mv_transform, proj_transform);
   GLint mat = glGetUniformLocationARB(prog, "matrix");
   glUniformMatrix4fvARB(mat, 1, GL_TRUE, proj_transform);
 
   glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, 0);
 }