Revert 281133 "chrome.hid: enrich model with report IDs"

Speculative revert to try and fix Win browser tests.

> chrome.hid: enrich model with report IDs
> 
> - add report IDs and max report size
> - don't expose sensitive usages
> 
> BUG=364423
> R=rockot@chromium.org
> TESTS=run device_unittests (HidReportDescriptorTest)
> 
> Review URL: https://codereview.chromium.org/317783010

TBR=jracle@logitech.com

Review URL: https://codereview.chromium.org/369923002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@281282 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 29 insertions, 141 deletions

diff --git a/device/hid/hid_report_descriptor.cc b/device/hid/hid_report_descriptor.cc
index a06d284..f2cb0f4 100644
--- a/device/hid/hid_report_descriptor.cc
+++ b/device/hid/hid_report_descriptor.cc
@@ -8,12 +8,6 @@
 
 namespace device {
 
-namespace {
-
-const int kBitsPerByte = 8;
-
-}  // namespace
-
 HidReportDescriptor::HidReportDescriptor(const uint8_t* bytes, size_t size) {
   size_t header_index = 0;
   HidReportDescriptorItem* item = NULL;
@@ -26,148 +20,42 @@ HidReportDescriptor::HidReportDescriptor(const uint8_t* bytes, size_t size) {
 
 HidReportDescriptor::~HidReportDescriptor() {}
 
-void HidReportDescriptor::GetDetails(
-    std::vector<HidCollectionInfo>* top_level_collections,
-    int* max_input_report_size,
-    int* max_output_report_size,
-    int* max_feature_report_size) {
-  DCHECK(top_level_collections);
-  DCHECK(max_input_report_size);
-  DCHECK(max_output_report_size);
-  DCHECK(max_feature_report_size);
-  STLClearObject(top_level_collections);
-
-  *max_input_report_size = 0;
-  *max_output_report_size = 0;
-  *max_feature_report_size = 0;
-
-  // Global tags data:
-  HidUsageAndPage::Page current_usage_page = HidUsageAndPage::kPageUndefined;
-  int current_report_count = 0;
-  int cached_report_count = 0;
-  int current_report_size = 0;
-  int cached_report_size = 0;
-  int current_input_report_size = 0;
-  int current_output_report_size = 0;
-  int current_feature_report_size = 0;
-
-  // Local tags data:
-  uint16_t current_usage = 0;
+void HidReportDescriptor::GetTopLevelCollections(
+    std::vector<HidUsageAndPage>* topLevelCollections) {
+  DCHECK(topLevelCollections);
+  STLClearObject(topLevelCollections);
 
   for (std::vector<linked_ptr<HidReportDescriptorItem> >::const_iterator
            items_iter = items().begin();
        items_iter != items().end();
        ++items_iter) {
-    linked_ptr<HidReportDescriptorItem> current_item = *items_iter;
-
-    switch (current_item->tag()) {
-      // Main tags:
-      case HidReportDescriptorItem::kTagCollection:
-        if (!current_item->parent()) {
-          // This is a top-level collection.
-          HidCollectionInfo collection;
-          collection.usage = HidUsageAndPage(current_usage, current_usage_page);
-          top_level_collections->push_back(collection);
-        }
-        break;
-      case HidReportDescriptorItem::kTagInput:
-        current_input_report_size += current_report_count * current_report_size;
-        break;
-      case HidReportDescriptorItem::kTagOutput:
-        current_output_report_size +=
-            current_report_count * current_report_size;
-        break;
-      case HidReportDescriptorItem::kTagFeature:
-        current_feature_report_size +=
-            current_report_count * current_report_size;
-        break;
-
-      // Global tags:
-      case HidReportDescriptorItem::kTagUsagePage:
-        current_usage_page =
-            (HidUsageAndPage::Page)current_item->GetShortData();
-        break;
-      case HidReportDescriptorItem::kTagReportId:
-        if (top_level_collections->size() > 0) {
-          // Store report ID.
-          top_level_collections->back().report_ids.insert(
-              current_item->GetShortData());
-
-          // We need to increase report sizes by report ID field length.
-          if (current_input_report_size > 0)
-            current_input_report_size += kBitsPerByte;
-          if (current_output_report_size > 0)
-            current_output_report_size += kBitsPerByte;
-          if (current_feature_report_size > 0)
-            current_feature_report_size += kBitsPerByte;
-
-          // Update max report sizes.
-          *max_input_report_size =
-              std::max(*max_input_report_size, current_input_report_size);
-          *max_output_report_size =
-              std::max(*max_output_report_size, current_output_report_size);
-          *max_feature_report_size =
-              std::max(*max_feature_report_size, current_feature_report_size);
-
-          // Set report sizes to be 1-byte long (report ID field).
-          current_input_report_size = 0;
-          current_output_report_size = 0;
-          current_feature_report_size = 0;
-        }
-        break;
-      case HidReportDescriptorItem::kTagReportCount:
-        current_report_count = current_item->GetShortData();
-        break;
-      case HidReportDescriptorItem::kTagReportSize:
-        current_report_size = current_item->GetShortData();
-        break;
-      case HidReportDescriptorItem::kTagPush:
-        // Cache report count and size.
-        cached_report_count = current_report_count;
-        cached_report_size = current_report_size;
-        break;
-      case HidReportDescriptorItem::kTagPop:
-        // Restore cache.
-        current_report_count = cached_report_count;
-        current_report_size = cached_report_size;
-        // Reset cache.
-        cached_report_count = 0;
-        cached_report_size = 0;
-        break;
-
-      // Local tags:
-      case HidReportDescriptorItem::kTagUsage:
-        current_usage = current_item->GetShortData();
-        break;
-
-      default:
-        break;
+    linked_ptr<HidReportDescriptorItem> item = *items_iter;
+
+    bool isTopLevelCollection =
+        item->tag() == HidReportDescriptorItem::kTagCollection &&
+        item->parent() == NULL;
+
+    if (isTopLevelCollection) {
+      uint16_t collection_usage = 0;
+      HidUsageAndPage::Page collection_usage_page =
+          HidUsageAndPage::kPageUndefined;
+
+      HidReportDescriptorItem* usage = item->previous();
+      if (usage && usage->tag() == HidReportDescriptorItem::kTagUsage) {
+        collection_usage = usage->GetShortData();
+      }
+
+      HidReportDescriptorItem* usage_page = usage->previous();
+      if (usage_page &&
+          usage_page->tag() == HidReportDescriptorItem::kTagUsagePage) {
+        collection_usage_page =
+            (HidUsageAndPage::Page)usage_page->GetShortData();
+      }
+
+      topLevelCollections->push_back(
+          HidUsageAndPage(collection_usage, collection_usage_page));
     }
   }
-
-  if (top_level_collections->size() > 0 &&
-      top_level_collections->back().report_ids.size() > 0) {
-    // We need to increase report sizes by report ID field length.
-    if (current_input_report_size > 0)
-      current_input_report_size += kBitsPerByte;
-    if (current_output_report_size > 0)
-      current_output_report_size += kBitsPerByte;
-    if (current_feature_report_size > 0)
-      current_feature_report_size += kBitsPerByte;
-  }
-
-  // Update max report sizes
-  *max_input_report_size =
-      std::max(*max_input_report_size, current_input_report_size);
-  *max_output_report_size =
-      std::max(*max_output_report_size, current_output_report_size);
-  *max_feature_report_size =
-      std::max(*max_feature_report_size, current_feature_report_size);
-
-  // Convert bits into bytes
-  *max_input_report_size /= kBitsPerByte;
-  *max_output_report_size /= kBitsPerByte;
-  *max_feature_report_size /= kBitsPerByte;
 }
 
 }  // namespace device