[Reland] Fix ReadPixels from float fbo buffer in ES2/WebGL1.

ui/gl/gl_version_info.cc

 // Copyright 2014 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_version_info.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/strings/string_util.h"
 
@@ skipping 25 matching lines @@
   is_desktop_core_profile =
       DesktopCoreCommonCheck(is_es, major_version, minor_version) &&
       extensions.find("GL_ARB_compatibility") == extensions.end();
 }
 
 GLVersionInfo::GLVersionInfo(const char* version_str, const char* renderer_str)
     : is_es(false),
       is_angle(false),
       major_version(0),
       minor_version(0),
+      is_es2(false),
       is_es3(false),
       is_desktop_core_profile(false) {
   if (version_str) {
     ParseVersionString(version_str, &major_version, &minor_version,
-                       &is_es, &is_es3);
+                       &is_es, &is_es2, &is_es3);
   }
   if (renderer_str) {
     is_angle = base::StartsWith(renderer_str, "ANGLE",
                                 base::CompareCase::SENSITIVE);
   }
 }
 
 void GLVersionInfo::ParseVersionString(const char* version_str,
                                        unsigned* major_version,
                                        unsigned* minor_version,
                                        bool* is_es,
+                                       bool* is_es2,
                                        bool* is_es3) {
   // Make sure the outputs are always initialized.
   *major_version = 0;
   *minor_version = 0;
   *is_es = false;
+  *is_es2 = false;
   *is_es3 = false;
   if (!version_str)
     return;
   std::string lstr(base::ToLowerASCII(version_str));
   *is_es = (lstr.length() > 12) && (lstr.substr(0, 9) == "opengl es");
   if (*is_es)
     lstr = lstr.substr(10, 3);
   base::StringTokenizer tokenizer(lstr.begin(), lstr.end(), ".");
   unsigned major, minor;
   if (tokenizer.GetNext() &&
       base::StringToUint(tokenizer.token_piece(), &major)) {
     *major_version = major;
     if (tokenizer.GetNext() &&
         base::StringToUint(tokenizer.token_piece(), &minor)) {
       *minor_version = minor;
     }
   }
+  if (*is_es && *major_version == 2)
+    *is_es2 = true;
   if (*is_es && *major_version == 3)
     *is_es3 = true;
   DCHECK(major_version != 0);
 }
 
 }  // namespace gfx