Use DIR_TEMP instead of DIR_EXE for content_shell.log

content_shell was trying to create log file in DIR_EXE. This doesn work
on platforms where the directory is not writable, particularly on
Fuchsia. Updated content_shell to use DIR_TEMP on Fuchsia.

Bug: 778467
Change-Id: I03198062e0c067340479209c99056a4e0b460ea4
Reviewed-on: https://chromium-review.googlesource.com/1054785
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558054}

content/shell/app/shell_main_delegate.cc

@@ -113,13 +113,15 @@ const GUID kContentShellProviderName = {
 #endif
 
 void InitLogging(const base::CommandLine& command_line) {
-  base::FilePath log_filename;
-  std::string filename = command_line.GetSwitchValueASCII(switches::kLogFile);
-  if (filename.empty()) {
+  base::FilePath log_filename =
+      command_line.GetSwitchValuePath(switches::kLogFile);
+  if (log_filename.empty()) {
+#if defined(OS_FUCHSIA)
+    base::PathService::Get(base::DIR_TEMP, &log_filename);
+#else
     base::PathService::Get(base::DIR_EXE, &log_filename);
+#endif
     log_filename = log_filename.AppendASCII("content_shell.log");
-  } else {
-    log_filename = base::FilePath::FromUTF8Unsafe(filename);
   }
 
   logging::LoggingSettings settings;