[PDF Ink Signatures] Add metric for PDFs loaded with V2 Ink annotations

Add a metric to track the number of PDFs loaded with V2 Ink annotations.
In order to do so, add a method in PDFiumEngine to check if a PDF has
any V2 Ink paths, without having to store and transform the paths.

This metric only tracks PDFs loaded for users with Ink2 enabled.

Bug: 380433757
Change-Id: I412ab1cb4a9b9a763e0f704527e234145b12e306
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6181044
Reviewed-by: Alan Screen <awscreen@chromium.org>
Commit-Queue: Andy Phan <andyphan@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1411985}

pdf/pdf_ink_metrics_handler.cc

@@ -158,4 +158,8 @@ void ReportEraseStroke(float size, ink::StrokeInput::ToolType tool_type) {
   ReportStrokeInputDeviceType(tool_type);
 }
 
+void RecordPdfLoadedWithV2InkAnnotations(bool has_annotations) {
+  base::UmaHistogramBoolean("PDF.LoadedWithV2InkAnnotations", has_annotations);
+}
+
 }  // namespace chrome_pdf

pdf/pdf_ink_metrics_handler.h

@@ -105,6 +105,8 @@ void ReportDrawStroke(PdfInkBrush::Type type,
 
 void ReportEraseStroke(float size, ink::StrokeInput::ToolType tool_type);
 
+void RecordPdfLoadedWithV2InkAnnotations(bool has_annotations);
+
 }  // namespace chrome_pdf
 
 #endif  // PDF_PDF_INK_METRICS_HANDLER_H_

pdf/pdf_view_web_plugin.cc

@@ -124,6 +124,7 @@
 #if BUILDFLAG(ENABLE_PDF_INK2)
 #include "base/memory/raw_ref.h"
 #include "pdf/pdf_ink_ids.h"
+#include "pdf/pdf_ink_metrics_handler.h"
 #include "pdf/pdf_ink_module.h"
 #include "pdf/pdf_ink_module_client.h"
 #include "third_party/skia/include/core/SkCanvas.h"
@@ -2472,6 +2473,14 @@ void PdfViewWebPlugin::RecordDocumentMetrics() {
     return;
 
   metrics_handler_->RecordDocumentMetrics(engine_->GetDocumentMetadata());
+
+#if BUILDFLAG(ENABLE_PDF_INK2)
+  // `metrics_handler_` is only initialized when not in Print Preview, so the
+  // V2 ink annotations load metric will not count Print Preview loads.
+  if (ink_module_) {
+    RecordPdfLoadedWithV2InkAnnotations(engine_->ContainsV2InkPath());
+  }
+#endif  // BUILDFLAG(ENABLE_PDF_INK2)
 }
 
 void PdfViewWebPlugin::SendAttachments() {

pdf/pdf_view_web_plugin_unittest.cc

@@ -19,6 +19,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/run_loop.h"
 #include "base/task/single_thread_task_runner.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/test/values_test_util.h"
 #include "base/time/time.h"
@@ -115,6 +116,11 @@ using ::testing::Return;
 using ::testing::SaveArg;
 using ::testing::SizeIs;
 
+#if BUILDFLAG(ENABLE_PDF_INK2)
+constexpr char kPdfLoadedWithV2InkAnnotationsMetric[] =
+    "PDF.LoadedWithV2InkAnnotations";
+#endif  // BUILDFLAG(ENABLE_PDF_INK2)
+
 // `kCanvasSize` needs to be big enough to hold plugin's snapshots during
 // testing.
 constexpr gfx::Size kCanvasSize(100, 100);
@@ -3040,6 +3046,51 @@ TEST_F(PdfViewWebPluginInk2SaveTest, AnnotationInEditMode) {
 
   pdf_receiver_.FlushForTesting();
 }
+
+using PdfViewWebPluginInkMetricTest = PdfViewWebPluginInkTest;
+
+TEST_F(PdfViewWebPluginInkMetricTest, LoadedWithoutV2InkAnnotations) {
+  base::HistogramTester histograms;
+
+  EXPECT_CALL(*engine_ptr_, ContainsV2InkPath()).WillOnce(Return(false));
+  plugin_->DocumentLoadComplete();
+
+  histograms.ExpectUniqueSample(kPdfLoadedWithV2InkAnnotationsMetric, false, 1);
+}
+
+TEST_F(PdfViewWebPluginInkMetricTest, LoadedWithV2InkAnnotations) {
+  base::HistogramTester histograms;
+
+  EXPECT_CALL(*engine_ptr_, ContainsV2InkPath()).WillOnce(Return(true));
+  plugin_->DocumentLoadComplete();
+
+  histograms.ExpectUniqueSample(kPdfLoadedWithV2InkAnnotationsMetric, true, 1);
+}
+
+class PdfViewWebPluginPrintPreviewInkMetricTest
+    : public PdfViewWebPluginPrintPreviewTest {
+ private:
+  base::test::ScopedFeatureList feature_list_{features::kPdfInk2};
+};
+
+TEST_F(PdfViewWebPluginPrintPreviewInkMetricTest,
+       LoadedWithV2InkAnnotationsDoesNotCountPrintPreview) {
+  base::HistogramTester histograms;
+
+  OnMessageWithEngineUpdate(ParseMessage(R"({
+    "type": "resetPrintPreviewMode",
+    "url": "chrome-untrusted://print/0/0/print.pdf",
+    "grayscale": false,
+    "pageCount": 1,
+  })"));
+
+  EXPECT_CALL(*engine_ptr_, ContainsV2InkPath()).Times(0);
+  plugin_->DocumentLoadComplete();
+
+  // The V2 ink annotations PDF load metric should not increment for Print
+  // Preview.
+  histograms.ExpectTotalCount(kPdfLoadedWithV2InkAnnotationsMetric, 0);
+}
 #endif  // BUILDFLAG(ENABLE_PDF_INK2)
 
 }  // namespace chrome_pdf

pdf/pdfium/pdfium_engine.cc

@@ -4459,6 +4459,15 @@ void PDFiumEngine::DiscardStroke(int page_index, InkStrokeId id) {
   ink_stroke_objects_map_.erase(it);
 }
 
+bool PDFiumEngine::ContainsV2InkPath() const {
+  for (const auto& page : pages_) {
+    if (PageContainsV2InkPath(page->GetPage())) {
+      return true;
+    }
+  }
+  return false;
+}
+
 std::map<InkModeledShapeId, ink::PartitionedMesh>
 PDFiumEngine::LoadV2InkPathsForPage(int page_index) {
   CHECK(PageIndexInBounds(page_index));

pdf/pdfium/pdfium_engine.h

@@ -396,6 +396,10 @@ class PDFiumEngine : public DocumentLoader::Client, public IFSDK_PAUSE {
   // `ApplyStroke()`. Virtual to support testing.
   virtual void DiscardStroke(int page_index, InkStrokeId id);
 
+  // Returns whether any of the pages contains a "V2" path created by Ink.
+  // Virtual to support testing.
+  virtual bool ContainsV2InkPath() const;
+
   // Loads "V2" Ink paths from a page in the PDF identified by `page_index`. The
   // `page_index` must be in bounds.
   //

pdf/pdfium/pdfium_engine_unittest.cc

@@ -2046,6 +2046,20 @@ TEST_P(PDFiumEngineInkTest, CannotSelectTextInAnnotationMode) {
   EXPECT_THAT(engine->GetSelectedText(), IsEmpty());
 }
 
+TEST_P(PDFiumEngineInkTest, ContainsV2InkPath) {
+  NiceMock<MockTestClient> client;
+  std::unique_ptr<PDFiumEngine> engine =
+      InitializeEngine(&client, FILE_PATH_LITERAL("blank.pdf"));
+  ASSERT_TRUE(engine);
+  ASSERT_EQ(1, engine->GetNumberOfPages());
+  EXPECT_FALSE(engine->ContainsV2InkPath());
+
+  engine = InitializeEngine(&client, FILE_PATH_LITERAL("ink_v2.pdf"));
+  ASSERT_TRUE(engine);
+  ASSERT_EQ(1, engine->GetNumberOfPages());
+  EXPECT_TRUE(engine->ContainsV2InkPath());
+}
+
 TEST_P(PDFiumEngineInkTest, LoadV2InkPathsForPage) {
   NiceMock<MockTestClient> client;
   std::unique_ptr<PDFiumEngine> engine =

pdf/pdfium/pdfium_ink_reader.cc

@@ -150,6 +150,20 @@ std::optional<ink::PartitionedMesh> ReadV2InkModeledShapeFromPath(
 
 }  // namespace
 
+bool PageContainsV2InkPath(FPDF_PAGE page) {
+  if (!page) {
+    return false;
+  }
+
+  const int page_object_count = FPDFPage_CountObjects(page);
+  for (int i = 0; i < page_object_count; ++i) {
+    if (IsV2InkPath(FPDFPage_GetObject(page, i))) {
+      return true;
+    }
+  }
+  return false;
+}
+
 std::vector<ReadV2InkPathResult> ReadV2InkPathsFromPageAsModeledShapes(
     FPDF_PAGE page) {
   std::vector<ReadV2InkPathResult> results;

pdf/pdfium/pdfium_ink_reader.h

@@ -24,6 +24,10 @@ struct ReadV2InkPathResult {
   ink::PartitionedMesh shape;
 };
 
+// Returns whether the given `page` contains a "V2" path created by Ink.
+// Returns false if `page` is null.
+bool PageContainsV2InkPath(FPDF_PAGE page);
+
 // For the given `page`, iterate through all page objects and import "V2" paths
 // created by Ink as ink::PartitionedMeshs. For each shape, also return its
 // associated page object. The shapes do not have outlines and are only suitable

pdf/test/test_pdfium_engine.h

@@ -109,6 +109,8 @@ class TestPDFiumEngine : public PDFiumEngine {
 
   MOCK_METHOD(void, DiscardStroke, (int, InkStrokeId), (override));
 
+  MOCK_METHOD(bool, ContainsV2InkPath, (), (const override));
+
   MOCK_METHOD((std::map<InkModeledShapeId, ink::PartitionedMesh>),
               LoadV2InkPathsForPage,
               (int),

tools/metrics/histograms/metadata/pdf/histograms.xml

@@ -146,6 +146,16 @@ chromium-metrics-reviews@google.com.
   </token>
 </histogram>
 
+<histogram name="PDF.LoadedWithV2InkAnnotations" enum="Boolean"
+    expires_after="2025-12-01">
+  <owner>andyphan@chromium.org</owner>
+  <owner>thestig@chromium.org</owner>
+  <summary>
+    Tracks the number of PDF documents loaded with existing V2 ink annotations
+    in the PDF viewer.
+  </summary>
+</histogram>
+
 <histogram name="PDF.LoadStatus2" enum="ChromePDFViewerLoadStatus"
     expires_after="2025-06-08">
   <owner>kmoon@chromium.org</owner>