Enable PDF accessibility when RenderFrame's accessibility mode changes.

components/pdf/renderer/pepper_pdf_host.cc

Index: components/pdf/renderer/pepper_pdf_host.cc
diff --git a/components/pdf/renderer/pepper_pdf_host.cc b/components/pdf/renderer/pepper_pdf_host.cc
index ab9418b33db14ef60cd5f21fd768156e506731a6..c7f2c4b4f8d7f3b7986d6aa30a6a518c37454905 100644
--- a/components/pdf/renderer/pepper_pdf_host.cc
+++ b/components/pdf/renderer/pepper_pdf_host.cc
@@ -237,7 +237,7 @@ void PepperPDFHost::CreatePdfAccessibilityTreeIfNeeded(
     content::PepperPluginInstance* instance) {
   if (!pdf_accessibility_tree_) {
     pdf_accessibility_tree_.reset(
-        new PdfAccessibilityTree(instance->GetRenderView()));
+        new PdfAccessibilityTree(instance->GetRenderFrame()));

[raymes, 2016/07/12 01:36:23]

There's already a function in RendererPpapiHost (host_) to get the RenderFrame.
I also /believe/ that the RenderFrame can be destroyed before this object, so we
shouldn't rely on the pointer being valid. Instead we should call
GetRenderFrameForInstance and cehck the result each time we need to use it.,

[dmazzoni, 2016/07/13 23:17:53]

Got it.

OK, now I'm passing RendererPpapiHost and PP_Instance to the
PdfAccessibilityTree constructor, that should resolve any
potential lifetime issues.

   }
 }