[unseasoned-pdf] Implement Find-in-Page

The CL implements find-in-page for unseasoned pdf-viewer.
- Register `PdfViewWebPlugin` as a plugin find handler.
- Notify `WebPluginContainer` the status of find requests in plugin.
- Scroll tick marks are not implemented as part of this CL.

Bug: 1199999
Change-Id: Ib468769c29e67c9a498b5000bbef72fcffa4f252
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3000502
Commit-Queue: Ankit Kumar 🌪️ <ankk@microsoft.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#898095}

pdf/pdf_view_web_plugin.cc

@@ -136,6 +136,16 @@ class BlinkContainerWrapper final : public PdfViewWebPlugin::ContainerWrapper {
 
   void Invalidate() override { container_->Invalidate(); }
 
+  void ReportFindInPageMatchCount(int identifier,
+                                  int total,
+                                  bool final_update) override {
+    container_->ReportFindInPageMatchCount(identifier, total, final_update);
+  }
+
+  void ReportFindInPageSelection(int identifier, int index) override {
+    container_->ReportFindInPageSelection(identifier, index);
+  }
+
   float DeviceScaleFactor() const override {
     return container_->DeviceScaleFactor();
   }
@@ -233,6 +243,10 @@ bool PdfViewWebPlugin::InitializeCommon(
   // TODO(crbug.com/1123621): Consider calling ValidateDocumentUrl() or
   // something like it once the process model has been finalized.
 
+  // Allow the plugin to handle find requests.
+  if (container)
+    container->UsePluginAsFindHandler();
+
   absl::optional<ParsedParams> params = ParseWebPluginParams(initial_params_);
 
   // The contents of `initial_params_` are no longer needed.
@@ -463,16 +477,19 @@ blink::WebURL PdfViewWebPlugin::LinkAtPosition(
 
 bool PdfViewWebPlugin::StartFind(const blink::WebString& search_text,
                                  bool case_sensitive,
-                                 int /*identifier*/) {
+                                 int identifier) {
+  find_identifier_ = identifier;
   engine()->StartFind(search_text.Utf8(), case_sensitive);
   return true;
 }
 
-void PdfViewWebPlugin::SelectFindResult(bool forward, int /*identifier*/) {
+void PdfViewWebPlugin::SelectFindResult(bool forward, int identifier) {
+  find_identifier_ = identifier;
   engine()->SelectFindResult(forward);
 }
 
 void PdfViewWebPlugin::StopFind() {
+  find_identifier_ = -1;
   engine()->StopFind();
   // TODO(crbug.com/1199999): Clear tickmarks on scroller when find is
   // dismissed.
@@ -490,9 +507,25 @@ void PdfViewWebPlugin::UpdateTickMarks(
     const std::vector<gfx::Rect>& tickmarks) {}
 
 void PdfViewWebPlugin::NotifyNumberOfFindResultsChanged(int total,
-                                                        bool final_result) {}
+                                                        bool final_result) {
+  // After stopping search and setting `find_identifier_` to -1 there still may
+  // be a NotifyNumberOfFindResultsChanged notification pending from engine.
+  // Just ignore them.
+  if (find_identifier_ == -1 || !container_wrapper_)
+    return;
+
+  container_wrapper_->ReportFindInPageMatchCount(find_identifier_, total,
+                                                 final_result);
+  // TODO(crbug.com/1199999): Set tickmarks on scroller.
+}
 
 void PdfViewWebPlugin::NotifySelectedFindResultChanged(int current_find_index) {
+  if (find_identifier_ == -1 || !container_wrapper_)
+    return;
+
+  DCHECK_GE(current_find_index, -1);
+  container_wrapper_->ReportFindInPageSelection(find_identifier_,
+                                                current_find_index + 1);
 }
 
 void PdfViewWebPlugin::Alert(const std::string& message) {

pdf/pdf_view_web_plugin.h

@@ -61,6 +61,15 @@ class PdfViewWebPlugin final : public PdfViewPluginBase,
     // page in it.
     virtual void Invalidate() = 0;
 
+    // Notify the web plugin container about the total matches of a find
+    // request.
+    virtual void ReportFindInPageMatchCount(int identifier,
+                                            int total,
+                                            bool final_update) = 0;
+
+    // Notify the web plugin container about the selected find result in plugin.
+    virtual void ReportFindInPageSelection(int identifier, int index) = 0;
+
     // Returns the device scale factor.
     virtual float DeviceScaleFactor() const = 0;
 
@@ -155,8 +164,8 @@ class PdfViewWebPlugin final : public PdfViewPluginBase,
   blink::WebURL LinkAtPosition(const gfx::Point& /*position*/) const override;
   bool StartFind(const blink::WebString& search_text,
                  bool case_sensitive,
-                 int /*identifier*/) override;
-  void SelectFindResult(bool forward, int /*identifier*/) override;
+                 int identifier) override;
+  void SelectFindResult(bool forward, int identifier) override;
   void StopFind() override;
   blink::WebTextInputType GetPluginTextInputType() override;
 
@@ -264,6 +273,10 @@ class PdfViewWebPlugin final : public PdfViewPluginBase,
 
   blink::WebString selected_text_;
 
+  // The id of the current find operation, or -1 if no current operation is
+  // present.
+  int find_identifier_ = -1;
+
   blink::WebTextInputType text_input_type_ =
       blink::WebTextInputType::kWebTextInputTypeNone;
 

pdf/pdf_view_web_plugin_unittest.cc

@@ -92,6 +92,10 @@ class FakeContainerWrapper final : public PdfViewWebPlugin::ContainerWrapper {
   // PdfViewWebPlugin::ContainerWrapper:
   void Invalidate() override {}
 
+  MOCK_METHOD(void, ReportFindInPageMatchCount, (int, int, bool), (override));
+
+  MOCK_METHOD(void, ReportFindInPageSelection, (int, int), (override));
+
   float DeviceScaleFactor() const override { return device_scale_; }
 
   MOCK_METHOD(void,