Update from https://crrev.com/309415

base/process/process_metrics.h

Index: base/process/process_metrics.h
diff --git a/base/process/process_metrics.h b/base/process/process_metrics.h
index ca23ac8984a35e111dd3608e6d62aedae932912c..d06e018e6074638edbfe09f8f767021339c596a7 100644
--- a/base/process/process_metrics.h
+++ b/base/process/process_metrics.h
@@ -231,6 +231,9 @@ class BASE_EXPORT ProcessMetrics {
 // Returns 0 if it can't compute the commit charge.
 BASE_EXPORT size_t GetSystemCommitCharge();
 
+// Returns the number of bytes in a memory page.
+BASE_EXPORT size_t GetPageSize();
+
 #if defined(OS_POSIX)
 // Returns the maximum number of file descriptors that can be open by a process
 // at once. If the number is unavailable, a conservative best guess is returned.