Moved serialization out of CRWSessionEntry.

ios/web/public/web_state/page_display_state.mm

Index: ios/web/public/web_state/page_display_state.mm
diff --git a/ios/web/public/web_state/page_display_state.mm b/ios/web/public/web_state/page_display_state.mm
index 378456b90118575f576be659f2cfa768a0462aac..6064fc5b7fd45622c271cfeff1d12fea7db93978 100644
--- a/ios/web/public/web_state/page_display_state.mm
+++ b/ios/web/public/web_state/page_display_state.mm
@@ -19,6 +19,12 @@
 inline bool StateValuesAreEqual(double value1, double value2) {
   return std::isnan(value1) ? std::isnan(value2) : value1 == value2;
 }
+// Returns the double stored under |key| in |serialization|, or NAN if it is not
+// set.
+inline double GetValue(NSString* key, NSDictionary* serialization) {
+  NSNumber* value = serialization[key];
+  return value ? [value doubleValue] : NAN;
+}
 }  // namespace
 
 PageScrollState::PageScrollState() : offset_x_(NAN), offset_y_(NAN) {
@@ -44,6 +50,16 @@ inline bool StateValuesAreEqual(double value1, double value2) {
   return !(*this == other);
 }
 
+NSString* PageScrollState::XOffsetKey() {
+  static NSString* const kXOffsetKey = @"scrollX";
+  return kXOffsetKey;
+}
+
+NSString* PageScrollState::YOffsetKey() {
+  static NSString* const kYOffsetKey = @"scrollY";
+  return kYOffsetKey;
+}
+
 PageZoomState::PageZoomState()
     : minimum_zoom_scale_(NAN), maximum_zoom_scale_(NAN), zoom_scale_(NAN) {
 }
@@ -76,6 +92,24 @@ inline bool StateValuesAreEqual(double value1, double value2) {
   return !(*this == other);
 }
 
+// static
+NSString* PageZoomState::MinZoomKey() {
+  static NSString* const kMinZoomKey = @"minZoom";
+  return kMinZoomKey;
+}
+
+// static
+NSString* PageZoomState::MaxZoomKey() {
+  static NSString* const kMaxZoomKey = @"maxZoom";
+  return kMaxZoomKey;
+}
+
+// static
+NSString* PageZoomState::ZoomKey() {
+  static NSString* const kZoomKey = @"zoom";
+  return kZoomKey;
+}
+
 PageDisplayState::PageDisplayState() {
 }
 
@@ -93,6 +127,13 @@ inline bool StateValuesAreEqual(double value1, double value2) {
       zoom_state_(minimum_zoom_scale, maximum_zoom_scale, zoom_scale) {
 }
 
+PageDisplayState::PageDisplayState(NSDictionary* serialization)
+    : PageDisplayState(GetValue(PageScrollState::XOffsetKey(), serialization),
+                       GetValue(PageScrollState::YOffsetKey(), serialization),
+                       GetValue(PageZoomState::MinZoomKey(), serialization),
+                       GetValue(PageZoomState::MaxZoomKey(), serialization),
+                       GetValue(PageZoomState::ZoomKey(), serialization)) {}
+
 PageDisplayState::~PageDisplayState() {
 }
 
@@ -109,4 +150,26 @@ inline bool StateValuesAreEqual(double value1, double value2) {
   return !(*this == other);
 }
 
+NSDictionary* PageDisplayState::GetSerialization() const {
+  return @{
+    PageScrollState::XOffsetKey() : @(scroll_state_.offset_x()),
+    PageScrollState::YOffsetKey() : @(scroll_state_.offset_y()),
+    PageZoomState::MinZoomKey() : @(zoom_state_.minimum_zoom_scale()),
+    PageZoomState::MaxZoomKey() : @(zoom_state_.maximum_zoom_scale()),
+    PageZoomState::ZoomKey() : @(zoom_state_.zoom_scale())
+  };
+}
+
+NSString* PageDisplayState::GetDescription() const {
+  NSString* const kPageScrollStateDescriptionFormat =
+      @"{ scrollOffset:(%0.2f, %0.2f), zoomScaleRange:(%0.2f, %0.2f), "
+      @"zoomScale:%0.2f }";
+  return [NSString stringWithFormat:kPageScrollStateDescriptionFormat,
+                                    scroll_state_.offset_x(),
+                                    scroll_state_.offset_y(),
+                                    zoom_state_.minimum_zoom_scale(),
+                                    zoom_state_.maximum_zoom_scale(),
+                                    zoom_state_.zoom_scale()];
+}
+
 }  // namespace web