Revert "dom: Remove PresentationAttributeCacheCleaner"

This reverts commit 6ed531bd.

Reason for revert: Caused multiple security regressions, see bug 810368.

Original change's description:
> dom: Remove PresentationAttributeCacheCleaner
> 
> PresentationAttributeCacheCleaner was introduced before purging memory
> was introduced.
> 
> This CL removes PresentationAttributeCacheCleaner to clear cache soon
> instead of delyaing with timers.
> 
> This is part of efforts to replace default timer task runners with
> other appropriate task runners in the renderer.
> 
> Bug: 624694, 804694
> Change-Id: I7ed775d4b998be82e35d8eefe1f7bd4e0d0145a2
> Reviewed-on: https://chromium-review.googlesource.com/903942
> Reviewed-by: Alexander Timin <altimin@chromium.org>
> Reviewed-by: Hayato Ito <hayato@chromium.org>
> Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#535306}

TBR=jbroman@chromium.org,hayato@chromium.org,hajimehoshi@chromium.org,altimin@chromium.org

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

Bug: 624694, 804694
Change-Id: I921fea361197deefd45968c07917cb5bc6fae0a4
Reviewed-on: https://chromium-review.googlesource.com/912091Reviewed-by: Abhishek Arya <inferno@chromium.org>
Commit-Queue: Abhishek Arya <inferno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535926}

third_party/WebKit/Source/core/dom/PresentationAttributeStyle.cpp

@@ -37,6 +37,7 @@
 #include "core/dom/Attribute.h"
 #include "core/dom/Element.h"
 #include "core/html/forms/HTMLInputElement.h"
+#include "platform/Timer.h"
 #include "platform/scheduler/child/web_scheduler.h"
 #include "platform/wtf/HashFunctions.h"
 #include "platform/wtf/HashMap.h"
@@ -80,6 +81,53 @@ static PresentationAttributeCache& GetPresentationAttributeCache() {
   return cache;
 }
 
+// This is a singleton (held via DEFINE_STATIC_LOCAL).
+// Thus it is appropriate to use the main thread's timer task runner, rather
+// than one associated with a particular frame.
+class PresentationAttributeCacheCleaner {
+  USING_FAST_MALLOC(PresentationAttributeCacheCleaner);
+
+ public:
+  PresentationAttributeCacheCleaner()
+      : hit_count_(0),
+        clean_timer_(
+            Platform::Current()->MainThread()->Scheduler()->TimerTaskRunner(),
+            this,
+            &PresentationAttributeCacheCleaner::CleanCache) {}
+
+  void DidHitPresentationAttributeCache() {
+    if (GetPresentationAttributeCache().size() <
+        kMinimumPresentationAttributeCacheSizeForCleaning)
+      return;
+
+    hit_count_++;
+
+    if (!clean_timer_.IsActive()) {
+      clean_timer_.StartOneShot(kPresentationAttributeCacheCleanTimeInSeconds,
+                                FROM_HERE);
+    }
+  }
+
+ private:
+  static const unsigned kPresentationAttributeCacheCleanTimeInSeconds = 60;
+  static const unsigned kMinimumPresentationAttributeCacheSizeForCleaning = 100;
+  static const unsigned kMinimumPresentationAttributeCacheHitCountPerMinute =
+      (100 * kPresentationAttributeCacheCleanTimeInSeconds) / 60;
+
+  void CleanCache(TimerBase* timer) {
+    DCHECK_EQ(timer, &clean_timer_);
+    unsigned hit_count = hit_count_;
+    hit_count_ = 0;
+    if (hit_count > kMinimumPresentationAttributeCacheHitCountPerMinute)
+      return;
+    GetPresentationAttributeCache().clear();
+  }
+
+  unsigned hit_count_;
+  TaskRunnerTimer<PresentationAttributeCacheCleaner> clean_timer_;
+  DISALLOW_COPY_AND_ASSIGN(PresentationAttributeCacheCleaner);
+};
+
 static bool AttributeNameSort(const std::pair<StringImpl*, AtomicString>& p1,
                               const std::pair<StringImpl*, AtomicString>& p2) {
   // Sort based on the attribute name pointers. It doesn't matter what the order
@@ -131,6 +179,8 @@ static unsigned ComputePresentationAttributeCacheHash(
 }
 
 CSSPropertyValueSet* ComputePresentationAttributeStyle(Element& element) {
+  DEFINE_STATIC_LOCAL(PresentationAttributeCacheCleaner, cache_cleaner, ());
+
   DCHECK(element.IsStyledElement());
 
   PresentationAttributeCacheKey cache_key;
@@ -152,13 +202,7 @@ CSSPropertyValueSet* ComputePresentationAttributeStyle(Element& element) {
   CSSPropertyValueSet* style = nullptr;
   if (cache_hash && cache_value->value) {
     style = cache_value->value->value;
-
-    static const unsigned kMinimumPresentationAttributeCacheSizeForCleaning =
-        100;
-    if (GetPresentationAttributeCache().size() >=
-        kMinimumPresentationAttributeCacheSizeForCleaning) {
-      GetPresentationAttributeCache().clear();
-    }
+    cache_cleaner.DidHitPresentationAttributeCache();
   } else {
     style = MutableCSSPropertyValueSet::Create(
         element.IsSVGElement() ? kSVGAttributeMode : kHTMLStandardMode);