Make callers of CommandLine use it via the base:: namespace.

tools/imagediff/image_diff.cc

Index: tools/imagediff/image_diff.cc
diff --git a/tools/imagediff/image_diff.cc b/tools/imagediff/image_diff.cc
index 6a9ebb9f9380105b7b790bca10192c640128b59a..608b7c96756ed49c96685851154f3a6c2b38c4a5 100644
--- a/tools/imagediff/image_diff.cc
+++ b/tools/imagediff/image_diff.cc
@@ -405,8 +405,9 @@ base::FilePath FilePathFromASCII(const std::string& str) {
 
 int main(int argc, const char* argv[]) {
   base::EnableTerminationOnHeapCorruption();
-  CommandLine::Init(argc, argv);
-  const CommandLine& parsed_command_line = *CommandLine::ForCurrentProcess();
+  base::CommandLine::Init(argc, argv);
+  const base::CommandLine& parsed_command_line =
+      *base::CommandLine::ForCurrentProcess();
   bool histograms = parsed_command_line.HasSwitch(kOptionCompareHistograms);
   if (parsed_command_line.HasSwitch(kOptionPollStdin)) {
     // Watch stdin for filenames.
@@ -432,7 +433,7 @@ int main(int argc, const char* argv[]) {
     return 0;
   }
 
-  const CommandLine::StringVector& args = parsed_command_line.GetArgs();
+  const base::CommandLine::StringVector& args = parsed_command_line.GetArgs();
   if (parsed_command_line.HasSwitch(kOptionGenerateDiff)) {
     if (args.size() == 3) {
       return DiffImages(base::FilePath(args[0]),