Replace FilePath declaration with file_path.h include

Fixes a clang error.  Also use "base::FilePath" since FilePath has been
moved to the base namespace.

BUG=chromium-os:39046
TEST=The following command passes:
USE="chrome_internal" CFLAGS="-clang -print-cmdline"
CXXFLAGS="-clang -print-cmdline" emerge-x86-alex crash-reporter

Change-Id: I7da82093c5685b5b556cba971b1e1b14ac0f59c4
Signed-off-by: Simon Que <sque@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/43577
Reviewed-by: Ben Chan <benchan@chromium.org>
diff --git a/crash_reporter/udev_collector.h b/crash_reporter/udev_collector.h
index acb09cb..29c19ef 100644
--- a/crash_reporter/udev_collector.h
+++ b/crash_reporter/udev_collector.h
@@ -7,11 +7,10 @@
 
 #include <string>
 
+#include "base/file_path.h"
 #include "crash-reporter/crash_collector.h"
 #include "gtest/gtest_prod.h"  // for FRIEND_TEST
 
-class FilePath;
-
 // Udev crash collector.
 class UdevCollector : public CrashCollector {
  public:
@@ -30,7 +29,7 @@
 
   // Mutator for unit testing.
   void set_log_config_path(const std::string& path) {
-    log_config_path_ = FilePath(path);
+    log_config_path_ = base::FilePath(path);
   }
 };