Add observer for BAAnnots from Javascript

This Cl moves the observer code from the CPDFSDK_Widget up into the
CPDFSDK_Annot base class and then adds a second observer for CPDFSDK_BAAnnot
objects.

This allows us to attach an observer to the Annot javascript class which will
update its internal pointer to the BAAnnot if the BAAnnot is destroyed by
the CPDFSDK_PageView being destroyed.

BUG=chromium:642307

Review-Url: https://codereview.chromium.org/2306663002

1 files changed, 31 insertions, 1 deletions

diff --git a/fpdfsdk/cpdfsdk_annot.cpp b/fpdfsdk/cpdfsdk_annot.cpp
index 59d8f24e82..353edaaaf9 100644
--- a/fpdfsdk/cpdfsdk_annot.cpp
+++ b/fpdfsdk/cpdfsdk_annot.cpp
@@ -9,6 +9,7 @@
 #include <algorithm>
 
 #include "fpdfsdk/include/fsdk_mgr.h"
+#include "third_party/base/stl_util.h"
 
 #ifdef PDF_ENABLE_XFA
 #include "fpdfsdk/fpdfxfa/include/fpdfxfa_doc.h"
@@ -21,10 +22,39 @@ const float kMinHeight = 1.0f;
 
 }  // namespace
 
+CPDFSDK_Annot::Observer::Observer(CPDFSDK_Annot** pWatchedPtr)
+    : m_pWatchedPtr(pWatchedPtr) {
+  (*m_pWatchedPtr)->AddObserver(this);
+}
+
+CPDFSDK_Annot::Observer::~Observer() {
+  if (m_pWatchedPtr)
+    (*m_pWatchedPtr)->RemoveObserver(this);
+}
+
+void CPDFSDK_Annot::Observer::OnAnnotDestroyed() {
+  ASSERT(m_pWatchedPtr);
+  *m_pWatchedPtr = nullptr;
+  m_pWatchedPtr = nullptr;
+}
+
 CPDFSDK_Annot::CPDFSDK_Annot(CPDFSDK_PageView* pPageView)
     : m_pPageView(pPageView), m_bSelected(FALSE) {}
 
-CPDFSDK_Annot::~CPDFSDK_Annot() {}
+CPDFSDK_Annot::~CPDFSDK_Annot() {
+  for (auto* pObserver : m_Observers)
+    pObserver->OnAnnotDestroyed();
+}
+
+void CPDFSDK_Annot::AddObserver(Observer* pObserver) {
+  ASSERT(!pdfium::ContainsKey(m_Observers, pObserver));
+  m_Observers.insert(pObserver);
+}
+
+void CPDFSDK_Annot::RemoveObserver(Observer* pObserver) {
+  ASSERT(pdfium::ContainsKey(m_Observers, pObserver));
+  m_Observers.erase(pObserver);
+}
 
 #ifdef PDF_ENABLE_XFA