Revert "Do not return heap size if there are multiple tabs in the same process"

This reverts commit 0edfddf2.

Reason for revert: Postponing change to get additional feedback from folks who consume this API.

Original change's description:
> Do not return heap size if there are multiple tabs in the same process
> 
> This CL changes MemoryInfo so that, when the heap statistics are calculated, the
> values for totalJSHeapSize and usedJSHeapSize are not used if the number of
> pages is greater than 1.
> 
> Bug: 807651
> Change-Id: I99bc52e0e2cb8e17c797fdb3868110fc409ad00e
> Reviewed-on: https://chromium-review.googlesource.com/904972
> Reviewed-by: Timothy Dresser <tdresser@chromium.org>
> Reviewed-by: Kentaro Hara <haraken@chromium.org>
> Commit-Queue: Nicolás Peña Moreno <npm@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#536755}

TBR=haraken@chromium.org,tdresser@chromium.org,npm@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 807651
Change-Id: I2897517db42c1c46af0ddeb16e190e4bb37d5884
Reviewed-on: https://chromium-review.googlesource.com/935501Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Timothy Dresser <tdresser@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538912}

third_party/WebKit/Source/core/timing/MemoryInfo.cpp

@@ -35,7 +35,6 @@
 #include "base/macros.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
-#include "core/page/Page.h"
 #include "platform/runtime_enabled_features.h"
 #include "platform/wtf/MathExtras.h"
 #include "platform/wtf/ThreadSpecific.h"
@@ -49,14 +48,9 @@ static const double kTwentyMinutesInSeconds = 20 * 60;
 static void GetHeapSize(HeapInfo& info) {
   v8::HeapStatistics heap_statistics;
   v8::Isolate::GetCurrent()->GetHeapStatistics(&heap_statistics);
-  info.js_heap_size_limit = heap_statistics.heap_size_limit();
-  // If there are multiple tabs from this renderer, do not report used and total
-  // js heap size.
-  if (Page::OrdinaryPages().size() > 1u)
-    return;
-
   info.used_js_heap_size = heap_statistics.used_heap_size();
   info.total_js_heap_size = heap_statistics.total_physical_size();
+  info.js_heap_size_limit = heap_statistics.heap_size_limit();
 }
 
 class HeapSizeCache {
@@ -92,16 +86,9 @@ class HeapSizeCache {
 
   void Update() {
     GetHeapSize(info_);
+    info_.used_js_heap_size = QuantizeMemorySize(info_.used_js_heap_size);
+    info_.total_js_heap_size = QuantizeMemorySize(info_.total_js_heap_size);
     info_.js_heap_size_limit = QuantizeMemorySize(info_.js_heap_size_limit);
-    DCHECK(info_.used_js_heap_size.has_value() ==
-           info_.total_js_heap_size.has_value());
-    if (!info_.used_js_heap_size.has_value())
-      return;
-
-    info_.used_js_heap_size =
-        QuantizeMemorySize(info_.used_js_heap_size.value());
-    info_.total_js_heap_size =
-        QuantizeMemorySize(info_.total_js_heap_size.value());
   }
 
   double last_update_time_;
@@ -169,22 +156,4 @@ MemoryInfo::MemoryInfo() {
     HeapSizeCache::ForCurrentThread().GetCachedHeapSize(info_);
 }
 
-size_t MemoryInfo::totalJSHeapSize(bool& is_null) const {
-  if (!info_.total_js_heap_size.has_value()) {
-    is_null = true;
-    return 0;
-  }
-  is_null = false;
-  return info_.total_js_heap_size.value();
-}
-
-size_t MemoryInfo::usedJSHeapSize(bool& is_null) const {
-  if (!info_.used_js_heap_size.has_value()) {
-    is_null = true;
-    return 0;
-  }
-  is_null = false;
-  return info_.used_js_heap_size.value();
-}
-
 }  // namespace blink

third_party/WebKit/Source/core/timing/MemoryInfo.h

@@ -35,16 +35,16 @@
 #include "platform/bindings/ScriptWrappable.h"
 #include "platform/heap/Handle.h"
 #include "platform/wtf/Allocator.h"
-#include "platform/wtf/Optional.h"
 
 namespace blink {
 
 struct HeapInfo {
   DISALLOW_NEW();
-  HeapInfo() : js_heap_size_limit(0) {}
+  HeapInfo()
+      : used_js_heap_size(0), total_js_heap_size(0), js_heap_size_limit(0) {}
 
-  Optional<size_t> used_js_heap_size;
-  Optional<size_t> total_js_heap_size;
+  size_t used_js_heap_size;
+  size_t total_js_heap_size;
   size_t js_heap_size_limit;
 };
 
@@ -54,8 +54,8 @@ class CORE_EXPORT MemoryInfo final : public ScriptWrappable {
  public:
   static MemoryInfo* Create() { return new MemoryInfo(); }
 
-  size_t totalJSHeapSize(bool& is_null) const;
-  size_t usedJSHeapSize(bool& is_null) const;
+  size_t totalJSHeapSize() const { return info_.total_js_heap_size; }
+  size_t usedJSHeapSize() const { return info_.used_js_heap_size; }
   size_t jsHeapSizeLimit() const { return info_.js_heap_size_limit; }
 
  private:

third_party/WebKit/Source/core/timing/MemoryInfo.idl

@@ -34,7 +34,7 @@
 [
     NoInterfaceObject
 ] interface MemoryInfo {
-    [Measure] readonly attribute unsigned long? totalJSHeapSize;
-    [Measure] readonly attribute unsigned long? usedJSHeapSize;
+    [Measure] readonly attribute unsigned long totalJSHeapSize;
+    [Measure] readonly attribute unsigned long usedJSHeapSize;
     [Measure] readonly attribute unsigned long jsHeapSizeLimit;
 };

third_party/WebKit/Source/core/timing/MemoryInfoTest.cpp

@@ -30,8 +30,6 @@
 
 #include "core/timing/MemoryInfo.h"
 
-#include "core/page/Page.h"
-#include "core/testing/DummyPageHolder.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
@@ -55,38 +53,4 @@ TEST(MemoryInfo, quantizeMemorySize) {
   EXPECT_EQ(10000000u, QuantizeMemorySize(0));
 }
 
-TEST(MemoryInfo, nullableValues) {
-  RuntimeEnabledFeatures::SetPreciseMemoryInfoEnabled(true);
-  // Having a single page, MemoryInfo provides all values.
-  std::unique_ptr<DummyPageHolder> page_holder = DummyPageHolder::Create();
-  Page::OrdinaryPages().insert(&page_holder->GetPage());
-  Persistent<MemoryInfo> info(MemoryInfo::Create());
-  bool is_null;
-  EXPECT_LT(0U, info->totalJSHeapSize(is_null));
-  EXPECT_FALSE(is_null);
-  EXPECT_LT(0U, info->usedJSHeapSize(is_null));
-  EXPECT_FALSE(is_null);
-  EXPECT_LT(0U, info->jsHeapSizeLimit());
-
-  // Now two pages total. MemoryInfo should only provide jsHeapSizeLimit.
-  std::unique_ptr<DummyPageHolder> other_page_holder =
-      DummyPageHolder::Create();
-  Page::OrdinaryPages().insert(&other_page_holder->GetPage());
-  info = MemoryInfo::Create();
-  EXPECT_EQ(0U, info->totalJSHeapSize(is_null));
-  EXPECT_TRUE(is_null);
-  EXPECT_EQ(0U, info->usedJSHeapSize(is_null));
-  EXPECT_TRUE(is_null);
-  EXPECT_LT(0U, info->jsHeapSizeLimit());
-
-  // Remove both pages. MemoryInfo should now provide all values.
-  Page::OrdinaryPages().clear();
-  info = MemoryInfo::Create();
-  EXPECT_LT(0U, info->totalJSHeapSize(is_null));
-  EXPECT_FALSE(is_null);
-  EXPECT_LT(0U, info->usedJSHeapSize(is_null));
-  EXPECT_FALSE(is_null);
-  EXPECT_LT(0U, info->jsHeapSizeLimit());
-}
-
 }  // namespace blink