[oilpan] Move incremental marking behind a build-time flag

Move Oilpan's incremental marking work behind a build-time flag
  enable_blink_heap_incremental_marking

Bug: chromium:757440
Change-Id: Id4adddcf0669dc165935eced90e8caefbb76a094
Reviewed-on: https://chromium-review.googlesource.com/822492
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524051}

third_party/WebKit/Source/platform/BUILD.gn

@@ -1481,6 +1481,7 @@ jumbo_component("platform") {
     "//services/service_manager/public/interfaces:interfaces_blink",
     "//skia",
     "//third_party:jpeg",
+    "//third_party/WebKit/Source/platform/heap",
     "//third_party/WebKit/Source/platform/wtf",
     "//third_party/WebKit/common:blink_common",
     "//third_party/WebKit/common:mojo_platform_bindings_blink",
@@ -1501,7 +1502,6 @@ jumbo_component("platform") {
     "//services/service_manager/public/cpp",
     "//third_party:freetype_harfbuzz",
     "//third_party/WebKit/Source/platform/blob",
-    "//third_party/WebKit/Source/platform/heap",
     "//third_party/WebKit/Source/platform/instrumentation",
     "//third_party/WebKit/Source/platform/loader",
     "//third_party/WebKit/Source/platform/media",
@@ -1912,6 +1912,10 @@ jumbo_source_set("blink_platform_unittests_sources") {
     "//third_party/WebKit/Source:config",
   ]
 
+  public_deps = [
+    "//third_party/WebKit/Source/platform/heap",
+  ]
+
   deps = [
     ":platform",
     ":test_support",

third_party/WebKit/Source/platform/heap/BUILD.gn

@@ -2,13 +2,29 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/buildflag_header.gni")
 import("//build/config/jumbo.gni")
 import("//testing/test.gni")
 
+declare_args() {
+  # Enables incremental marking in Oilpan.
+  enable_blink_heap_incremental_marking = false
+}
+
+buildflag_header("blink_heap_incremental_marking") {
+  header = "IncrementalMarking.h"
+
+  header_dir = "blink/platform/heap"
+
+  flags = [
+    "BLINK_HEAP_INCREMENTAL_MARKING=$enable_blink_heap_incremental_marking",
+  ]
+}
+
 jumbo_source_set("heap") {
   # This target is a logical part of the platform and only the platform target
   # should depend on it.
-  visibility = [ "//third_party/WebKit/Source/platform" ]
+  visibility = [ "//third_party/WebKit/Source/platform:*" ]
 
   sources = [
     "BlinkGC.h",
@@ -74,6 +90,7 @@ jumbo_source_set("heap") {
   ]
 
   public_deps = [
+    ":blink_heap_incremental_marking",
     "//third_party/WebKit/public:blink_headers",
   ]
 }

third_party/WebKit/Source/platform/heap/IncrementalMarkingTest.cpp

@@ -5,13 +5,13 @@
 #include "platform/heap/CallbackStack.h"
 #include "platform/heap/GarbageCollected.h"
 #include "platform/heap/Heap.h"
+#include "platform/heap/IncrementalMarking.h"
 #include "platform/heap/Member.h"
 #include "platform/heap/ThreadState.h"
 #include "platform/heap/TraceTraits.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-// TODO(mlippautz): Replace with proper build flag.
-#if 0
+#if BUILDFLAG(BLINK_HEAP_INCREMENTAL_MARKING)
 
 namespace blink {
 namespace incremental_marking_test {
@@ -214,4 +214,4 @@ TEST(IncrementalMarkingTest, NoWriteBarrierOnMarkedMixinApplication) {
 }  // namespace incremental_marking_test
 }  // namespace blink
 
-#endif
+#endif  // BUILDFLAG(BLINK_HEAP_INCREMENTAL_MARKING)

third_party/WebKit/Source/platform/heap/Member.h

@@ -7,6 +7,7 @@
 
 #include "platform/heap/Heap.h"
 #include "platform/heap/HeapPage.h"
+#include "platform/heap/IncrementalMarking.h"
 #include "platform/wtf/Allocator.h"
 #include "platform/wtf/HashFunctions.h"
 #include "platform/wtf/HashTraits.h"
@@ -249,8 +250,7 @@ class Member : public MemberBase<T, TracenessMemberConfiguration::kTraced> {
 
  protected:
   ALWAYS_INLINE void WriteBarrier(const T* value) const {
-// TODO(mlippautz): Replace with proper build flag.
-#if 0
+#if BUILDFLAG(BLINK_HEAP_INCREMENTAL_MARKING)
     if (value) {
       // The following method for retrieving a page works as allocation of
       // mixins on large object pages is prohibited.
@@ -260,7 +260,7 @@ class Member : public MemberBase<T, TracenessMemberConfiguration::kTraced> {
         ThreadState::Current()->Heap().WriteBarrierInternal(page, value);
       }
     }
-#endif
+#endif  // BUILDFLAG(BLINK_HEAP_INCREMENTAL_MARKING)
   }
 };
 

third_party/WebKit/Source/platform/heap/ThreadState.cpp

@@ -44,6 +44,7 @@
 #include "platform/heap/Handle.h"
 #include "platform/heap/Heap.h"
 #include "platform/heap/HeapCompact.h"
+#include "platform/heap/IncrementalMarking.h"
 #include "platform/heap/PagePool.h"
 #include "platform/heap/SafePoint.h"
 #include "platform/heap/Visitor.h"
@@ -364,15 +365,14 @@ bool ThreadState::JudgeGCThreshold(size_t allocated_object_size_threshold,
 }
 
 bool ThreadState::ShouldScheduleIncrementalMarking() const {
-// TODO(mlippautz): Replace with proper build flag.
-#if 0
+#if BUILDFLAG(BLINK_HEAP_INCREMENTAL_MARKING)
   // TODO(mlippautz): For now immediately schedule incremental marking if
   // the runtime flag is provided, basically exercising a stress test.
   return (GcState() == kNoGCScheduled || GcState() == kSweeping) &&
          RuntimeEnabledFeatures::HeapIncrementalMarkingEnabled();
 #else
   return false;
-#endif
+#endif  // BUILDFLAG(BLINK_HEAP_INCREMENTAL_MARKING)
 }
 
 bool ThreadState::ShouldScheduleIdleGC() {