Enables the allocator shim by default on iOS.

Compiles the SamplingHeapProfiler, with associated tests, and adds iOS
to the list of platforms which use the allocator shim.

BUG=1075702

Change-Id: I4e20027633f0e4ca9b49c37b110f6548ae8ace46
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2168810
Commit-Queue: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#763472}

base/BUILD.gn

@@ -1186,6 +1186,10 @@ jumbo_component("base") {
 
   if (is_ios) {
     sources += [
+      "allocator/allocator_interception_mac.h",
+      "allocator/allocator_interception_mac.mm",
+      "allocator/malloc_zone_functions_mac.cc",
+      "allocator/malloc_zone_functions_mac.h",
       "critical_closure_internal_ios.mm",
       "ios/block_types.h",
       "ios/crb_protocol_observers.h",
@@ -1362,7 +1366,7 @@ jumbo_component("base") {
         "allocator/allocator_shim_override_linker_wrapped_symbols.h",
       ]
       all_dependent_configs += [ "//base/allocator:wrap_malloc_symbols" ]
-    } else if (is_mac) {
+    } else if (is_mac || is_ios) {
       sources += [
         "allocator/allocator_shim_default_dispatch_to_mac_zoned_malloc.cc",
         "allocator/allocator_shim_default_dispatch_to_mac_zoned_malloc.h",
@@ -1969,10 +1973,6 @@ jumbo_component("base") {
       "process/process_iterator.h",
       "process/process_metrics_posix.cc",
       "process/process_posix.cc",
-      "sampling_heap_profiler/poisson_allocation_sampler.cc",
-      "sampling_heap_profiler/poisson_allocation_sampler.h",
-      "sampling_heap_profiler/sampling_heap_profiler.cc",
-      "sampling_heap_profiler/sampling_heap_profiler.h",
       "sync_socket.h",
       "sync_socket_posix.cc",
       "synchronization/waitable_event_watcher.h",
@@ -2984,6 +2984,8 @@ test("base_unittests") {
 
   if (is_ios) {
     sources += [
+      "allocator/allocator_interception_mac_unittest.mm",
+      "allocator/malloc_zone_functions_mac_unittest.cc",
       "ios/crb_protocol_observers_unittest.mm",
       "ios/device_util_unittest.mm",
       "ios/weak_nsobject_unittest.mm",

base/allocator/allocator.gni

@@ -17,7 +17,7 @@ if (is_android || is_mac || is_ios || is_asan || is_lsan || is_tsan ||
 # The debug CRT on Windows has some debug features that are incompatible with
 # the shim. NaCl in particular does seem to link some binaries statically
 # against the debug CRT with "is_nacl=false".
-if ((is_linux || is_android || is_mac ||
+if ((is_linux || is_android || is_mac || is_ios ||
      (is_win && !is_component_build && !is_debug)) && !is_asan && !is_hwasan &&
     !is_lsan && !is_tsan && !is_msan) {
   _default_use_allocator_shim = true
@@ -37,9 +37,11 @@ assert(use_allocator == "none" || use_allocator == "tcmalloc")
 
 assert(!is_win || use_allocator == "none", "Tcmalloc doesn't work on Windows.")
 assert(!is_mac || use_allocator == "none", "Tcmalloc doesn't work on macOS.")
+assert(!is_ios || use_allocator == "none", "Tcmalloc doesn't work on iOS.")
 
-assert(!use_allocator_shim || is_linux || is_android || is_win || is_mac,
-       "use_allocator_shim works only on Android, Linux, macOS, and Windows.")
+assert(
+    !use_allocator_shim || is_linux || is_android || is_win || is_mac || is_ios,
+    "use_allocator_shim works only on Android, Linux, macOS, iOS, and Windows.")
 
 if (is_win && use_allocator_shim) {
   assert(!is_component_build,

base/allocator/allocator_interception_mac.mm

@@ -31,13 +31,18 @@
 #include "base/bind.h"
 #include "base/bits.h"
 #include "base/logging.h"
-#include "base/mac/mac_util.h"
 #include "base/mac/mach_logging.h"
 #include "base/process/memory.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "build/build_config.h"
 #include "third_party/apple_apsl/CFBase.h"
 
+#if defined(OS_IOS)
+#include "base/ios/ios_util.h"
+#else
+#include "base/mac/mac_util.h"
+#endif
+
 namespace base {
 namespace allocator {
 
@@ -208,7 +213,11 @@ void* oom_killer_memalign_purgeable(struct _malloc_zone_t* zone,
 // === Core Foundation CFAllocators ===
 
 bool CanGetContextForCFAllocator() {
+#if defined(OS_IOS)
+  return !base::ios::IsRunningOnOrLater(14, 0, 0);
+#else
   return !base::mac::IsOSLaterThan10_15_DontCallThis();
+#endif
 }
 
 CFAllocatorContext* ContextForCFAllocator(CFAllocatorRef allocator) {

base/sampling_heap_profiler/sampling_heap_profiler_unittest.cc

@@ -116,7 +116,13 @@ TEST_F(SamplingHeapProfilerTest, IntervalRandomizationSanity) {
   EXPECT_NEAR(1000, mean_samples, 100);  // 10% tolerance.
 }
 
+#if defined(OS_IOS)
+// iOS devices generally have ~4GB of RAM with no swap and therefore need a
+// lower allocation limit here.
+const int kNumberOfAllocations = 1000;
+#else
 const int kNumberOfAllocations = 10000;
+#endif
 
 NOINLINE void Allocate1() {
   void* p = malloc(400);