Move malloc/partition_alloc memory usage functions to base

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 b1f52cadbe2a7da8ab7160485ea1d30e21499b0b..717cb0097680af4934b6d2ac74b6bad589bcd190 100644
--- a/base/process/process_metrics.h
+++ b/base/process/process_metrics.h
@@ -230,6 +230,9 @@ class BASE_EXPORT ProcessMetrics {
   uint64_t GetVmSwapBytes() const;
 #endif  // defined(OS_LINUX) || defined(OS_ANDROID)
 
+  // Returns total memory usage of malloc.
+  size_t GetMallocUsage();
+
  private:
 #if !defined(OS_MACOSX) || defined(OS_IOS)
   explicit ProcessMetrics(ProcessHandle process);