Add //build/config/linux/dri to extract path to dri drivers

The dri drivers path is the variable 'dridriverdir' in 'dri.pc'

If found then translate it to the macro DRI_DRIVER_DIR.

It can be useful in various places instead of guessing the path.
For now only use it in gpu_sandbox_hook_linux except for ChromeOS.

Bug: 787787
Change-Id: I7fef8606a4f2cbc04233af820a91cf12a4c7a9a5
Reviewed-on: https://chromium-review.googlesource.com/785371Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Julien Isorce <julien.isorce@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519658}

build/config/linux/dri/BUILD.gn

+# Copyright 2017 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.
+
+import("//build/config/linux/pkg_config.gni")
+
+assert(is_linux, "This file should only be referenced on Linux")
+
+pkg_config("dri") {
+  packages = [ "dri" ]
+  dri_driver_dir = exec_script(pkg_config_script,
+                               pkg_config_args + [
+                                     "--dridriverdir",
+                                     "dri",
+                                   ],
+                               "string")
+  defines = [ "DRI_DRIVER_DIR=\"$dri_driver_dir\"" ]
+}

build/config/linux/pkg-config.py

@@ -123,6 +123,7 @@ def main():
   parser.add_option('--atleast-version', action='store',
                     dest='atleast_version', type='string')
   parser.add_option('--libdir', action='store_true', dest='libdir')
+  parser.add_option('--dridriverdir', action='store_true', dest='dridriverdir')
   (options, args) = parser.parse_args()
 
   # Make a list of regular expressions to strip out.
@@ -162,6 +163,18 @@ def main():
     sys.stdout.write(libdir.strip())
     return 0
 
+  if options.dridriverdir:
+    cmd = [options.pkg_config, "--variable=dridriverdir"] + args
+    if options.debug:
+      sys.stderr.write('Running: %s\n' % cmd)
+    try:
+      dridriverdir = subprocess.check_output(cmd)
+    except:
+      print "Error from pkg-config."
+      return 1
+    sys.stdout.write(dridriverdir.strip())
+    return
+
   cmd = [options.pkg_config, "--cflags", "--libs"] + args
   if options.debug:
     sys.stderr.write('Running: %s\n' % ' '.join(cmd))

build/dotfile_settings.gni

@@ -17,6 +17,7 @@ build_dotfile_settings = {
     "//build/config/linux/BUILD.gn",
     "//build/config/linux/pkg_config.gni",
     "//build/config/linux/atk/BUILD.gn",
+    "//build/config/linux/dri/BUILD.gn",
     "//build/config/mac/mac_sdk.gni",
     "//build/config/mac/rules.gni",
     "//build/config/posix/BUILD.gn",

content/gpu/BUILD.gn

@@ -119,4 +119,8 @@ target(link_target_type, "gpu_sources") {
   if (enable_vulkan) {
     deps += [ "//gpu/vulkan" ]
   }
+
+  if (is_desktop_linux) {
+    configs += [ "//build/config/linux/dri" ]
+  }
 }

content/gpu/gpu_sandbox_hook_linux.cc

@@ -238,7 +238,12 @@ bool LoadAmdGpuLibraries() {
     LOG(ERROR) << "dlopen(libglapi.so) failed with error: " << dlerror();
     return false;
   }
-  if (nullptr == dlopen("/usr/lib64/dri/radeonsi_dri.so", dlopen_flag)) {
+
+  const char* radeonsi_lib = "/usr/lib64/dri/radeonsi_dri.so";
+#if defined(DRI_DRIVER_DIR)
+  radeonsi_lib = DRI_DRIVER_DIR "/radeonsi_dri.so";
+#endif
+  if (nullptr == dlopen(radeonsi_lib, dlopen_flag)) {
     LOG(ERROR) << "dlopen(radeonsi_dri.so) failed with error: " << dlerror();
     return false;
   }