Retain pp::ImageData while there are pending paints against it.

The ImageData might get destroyed while the paints are still
pending. Typically, the paints are then cancelled thereafter so
no harm comes from the dangling references, but this patch avoids
creating them in the first place.

The remaining changes are consequences of ProgressivePaint
becoming non-POD, and converting to protected members. Also
use scoped FPDF classes while we're at it.

Bug: 838886
Change-Id: Ic933350ac9e981da58f1f841968dc89fb8518974
Reviewed-on: https://chromium-review.googlesource.com/1054502Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557724}

pdf/BUILD.gn

@@ -133,6 +133,7 @@ if (enable_pdf) {
 
     if (pdf_engine == 0) {
       sources += [ "pdfium/findtext_unittest.cc" ]
+      include_dirs = [ "//third_party/pdfium" ]
     }
   }
 } else {

pdf/pdfium/pdfium_engine.h

@@ -29,6 +29,7 @@
 #include "ppapi/cpp/point.h"
 #include "ppapi/cpp/var_array.h"
 #include "ppapi/utility/completion_callback_factory.h"
+#include "third_party/pdfium/public/cpp/fpdf_scopers.h"
 #include "third_party/pdfium/public/fpdf_dataavail.h"
 #include "third_party/pdfium/public/fpdf_formfill.h"
 #include "third_party/pdfium/public/fpdf_progressive.h"
@@ -381,8 +382,8 @@ class PDFiumEngine : public PDFEngine,
   int GetProgressiveIndex(int page_index) const;
 
   // Creates a FPDF_BITMAP from a rectangle in screen coordinates.
-  FPDF_BITMAP CreateBitmap(const pp::Rect& rect,
-                           pp::ImageData* image_data) const;
+  ScopedFPDFBitmap CreateBitmap(const pp::Rect& rect,
+                                pp::ImageData* image_data) const;
 
   // Given a rectangle in screen coordinates, returns the coordinates in the
   // units that PDFium rendering functions expect.
@@ -637,13 +638,33 @@ class PDFiumEngine : public PDFEngine,
   std::string link_under_cursor_;
 
   // Pending progressive paints.
-  struct ProgressivePaint {
-    pp::Rect rect;  // In screen coordinates.
-    FPDF_BITMAP bitmap;
-    int page_index;
+  class ProgressivePaint {
+   public:
+    ProgressivePaint(int page_index, const pp::Rect& rect);
+    ProgressivePaint(ProgressivePaint&& that);
+    ~ProgressivePaint();
+
+    ProgressivePaint& operator=(ProgressivePaint&& that);
+
+    int page_index() const { return page_index_; }
+    const pp::Rect& rect() const { return rect_; }
+    FPDF_BITMAP bitmap() const { return bitmap_.get(); }
+    bool painted() const { return painted_; }
+
+    void set_painted(bool enable) { painted_ = enable; }
+    void SetBitmapAndImageData(ScopedFPDFBitmap bitmap,
+                               pp::ImageData image_data);
+
+   private:
+    int page_index_;
+    pp::Rect rect_;             // In screen coordinates.
+    pp::ImageData image_data_;  // Maintains reference while |bitmap_| exists.
+    ScopedFPDFBitmap bitmap_;   // Must come after |image_data_|.
     // Temporary used to figure out if in a series of Paint() calls whether this
     // pending paint was updated or not.
-    bool painted_;
+    bool painted_ = false;
+
+    DISALLOW_COPY_AND_ASSIGN(ProgressivePaint);
   };
   std::vector<ProgressivePaint> progressive_paints_;