Set GLSL "precision" only if using OpenGL ES.

gpu/perftests/texture_upload_perftest.cc

 // Copyright 2015 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 <vector>
 
 #include "base/containers/small_map.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
@@ skipping 26 matching lines @@
   uniform vec2 translation;
   attribute vec2 a_position;
   attribute vec2 a_texCoord;
   varying vec2 v_texCoord;
   void main() {
     gl_Position = vec4(
         translation.x + a_position.x, translation.y + a_position.y, 0.0, 1.0);
     v_texCoord = a_texCoord;
   }
 );
+const char kShaderDefaultFloatPrecision[] =
+SHADER(
+  precision mediump float;
+);
 const char kFragmentShader[] =
 SHADER(
-  precision mediump float;
   uniform sampler2D a_texture;
   varying vec2 v_texCoord;
   void main() {
     gl_FragColor = texture2D(a_texture, v_texCoord);
   }
 );
 // clang-format on
 
 void CheckNoGlError() {
   CHECK_EQ(static_cast<GLenum>(GL_NO_ERROR), glGetError());
@@ skipping 120 matching lines @@
     if (gpu_timing_client_->IsAvailable()) {
       LOG(INFO) << "Gpu timing initialized with timer type: "
                 << gpu_timing_client_->GetTimerTypeName();
       gpu_timing_client_->InvalidateTimerOffset();
     } else {
       LOG(WARNING) << "Can't initialize gpu timing";
     }
     // Prepare a simple program and a vertex buffer that will be
     // used to draw a quad on the offscreen surface.
     vertex_shader_ = LoadShader(GL_VERTEX_SHADER, kVertexShader);
-    fragment_shader_ = LoadShader(GL_FRAGMENT_SHADER, kFragmentShader);
+
+    bool is_gles = gfx::GetGLImplementation() == gfx::kGLImplementationEGLGLES2;
+    fragment_shader_ = LoadShader(
+        GL_FRAGMENT_SHADER,
+        base::StringPrintf("%s%s", is_gles ? kShaderDefaultFloatPrecision : "",
+                           kFragmentShader).c_str());
     program_object_ = glCreateProgram();
     CHECK_NE(0u, program_object_);
 
     glAttachShader(program_object_, vertex_shader_);
     glAttachShader(program_object_, fragment_shader_);
     glBindAttribLocation(program_object_, 0, "a_position");
     glBindAttribLocation(program_object_, 1, "a_texCoord");
     glLinkProgram(program_object_);
 
     GLint linked = -1;
@@ skipping 263 matching lines @@
                           gpu_timing_client_->CheckAndResetTimerErrors();
   if (!gpu_timer_errors) {
     upload_and_draw_timers.GetAsMeasurement("upload_and_draw")
         .PrintResult("renaming");
     finish_timers.GetAsMeasurement("finish").PrintResult("renaming");
   }
 }
 
 }  // namespace
 }  // namespace gpu