mac/arm: Get process_metrics_mac.cc to compile

Bug: 1098899
Change-Id: Iae357fc998a662ed23bf1496a4ec21a12593f2cf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2285331
Commit-Queue: Nico Weber <thakis@chromium.org>
Auto-Submit: Nico Weber <thakis@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786042}

base/process/process_metrics_mac.cc

@@ -22,13 +22,14 @@
 #include "base/numerics/safe_math.h"
 #include "base/process/process_metrics_iocounters.h"
 #include "base/time/time.h"
+#include "build/build_config.h"
 
 namespace {
 
 // This is a standin for the private pm_task_energy_data_t struct.
 struct OpaquePMTaskEnergyData {
   // Empirical size of the private struct.
-  uint8_t data[384];
+  uint8_t data[408];
 };
 
 // Sample everything but network usage, since fetching network
@@ -300,7 +301,12 @@ bool GetSystemMemoryInfo(SystemMemoryInfoKB* meminfo) {
   }
   DCHECK_EQ(HOST_VM_INFO64_COUNT, count);
 
+#if defined(ARCH_CPU_ARM64)
+  // PAGE_SIZE is vm_page_size on arm, which isn't constexpr.
+  DCHECK_EQ(PAGE_SIZE % 1024, 0) << "Invalid page size";
+#else
   static_assert(PAGE_SIZE % 1024 == 0, "Invalid page size");
+#endif
   meminfo->free = saturated_cast<int>(
       PAGE_SIZE / 1024 * (vm_info.free_count - vm_info.speculative_count));
   meminfo->speculative =