On Linux rework driver_version/vendor extraction from gl version

gpu/config/gpu_info_collector_linux.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 "gpu/config/gpu_info_collector_linux.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <vector>
@@ skipping 229 matching lines @@
   }
 
   gpu_info->basic_info_state = result;
   return result;
 }
 
 CollectInfoResult CollectDriverInfoGL(GPUInfo* gpu_info) {
   DCHECK(gpu_info);
 
   std::string gl_version = gpu_info->gl_version;
-  if (base::StartsWith(gl_version, "OpenGL ES", base::CompareCase::SENSITIVE))
-    gl_version = gl_version.substr(10);
   std::vector<std::string> pieces = base::SplitString(
       gl_version, base::kWhitespaceASCII, base::KEEP_WHITESPACE,
       base::SPLIT_WANT_NONEMPTY);
   // In linux, the gl version string might be in the format of
   //   GLVersion DriverVendor DriverVersion
   if (pieces.size() < 3)
     return kCollectInfoNonFatalFailure;
 
-  std::string driver_version = pieces[2];
-  size_t pos = driver_version.find_first_not_of("0123456789.");
-  if (pos == 0)
+  // Search from the end for the first piece that contains at least one digit.

[Ken Russell (switch to Gerrit), 2016/07/21 23:54:54]

Why not just use a regexp? Something which matches

  [0-9].[0-9](.[0-9])?.*

I think this should be looking for something which starts with a number, but
that could be conflated with the git hashes. Let's just do something better.

[Julien Isorce Samsung, 2016/07/22 07:38:29]

Done.

+  // But assume the driver version cannot be the first two pieces.
+  std::string driver_version;
+  auto it = pieces.rbegin();
+  while (it + 2 != pieces.rend()) {

[Ken Russell (switch to Gerrit), 2016/07/21 23:54:54]

This looks risky. Please do something else which is more resilient to
out-of-bounds accesses. Perhaps 

  while (pieces.rend() - it > 2) {
  }

[Julien Isorce Samsung, 2016/07/22 07:38:29]

Done.

+    size_t pos = it->find_first_not_of("0123456789.");
+    if (pos != 0) {
+      driver_version = it->substr(0, pos);
+      break;
+    }
+    ++it;
+  }
+
+  if (driver_version.empty())
     return kCollectInfoNonFatalFailure;
-  if (pos != std::string::npos)
-    driver_version = driver_version.substr(0, pos);
 
-  gpu_info->driver_vendor = pieces[1];
+  gpu_info->driver_vendor = *(++it);
   gpu_info->driver_version = driver_version;
   return kCollectInfoSuccess;
 }
 
 void MergeGPUInfo(GPUInfo* basic_gpu_info,
                   const GPUInfo& context_gpu_info) {
   MergeGPUInfoGL(basic_gpu_info, context_gpu_info);
 }
 
 }  // namespace gpu