Use same_document term instead of same_page in FrameNavigationState

Old name was presumably used to match was_within_same_page IPC, but
SameDocument name better reflects the the type of the navigation
(navigation did not change the document object).

This change will make naming more consistent with the rest of Chromium
code.

BUG=695189

Review-Url: https://codereview.chromium.org/2971073002
Cr-Commit-Position: refs/heads/master@{#487623}

chrome/browser/extensions/api/web_navigation/frame_navigation_state.cc

@@ -69,12 +69,12 @@ bool FrameNavigationState::CanSendEvents(
 void FrameNavigationState::StartTrackingDocumentLoad(
     content::RenderFrameHost* frame_host,
     const GURL& url,
-    bool is_same_page,
+    bool is_same_document,
     bool is_error_page) {
   FrameState& frame_state = frame_host_state_map_[frame_host];
   frame_state.error_occurred = is_error_page;
   frame_state.url = url;
-  if (!is_same_page) {
+  if (!is_same_document) {
     frame_state.is_loading = true;
     frame_state.is_parsing = true;
   }

chrome/browser/extensions/api/web_navigation/frame_navigation_state.h

@@ -41,7 +41,7 @@ class FrameNavigationState {
   // Starts to track a document load in |frame_host| to |url|.
   void StartTrackingDocumentLoad(content::RenderFrameHost* frame_host,
                                  const GURL& url,
-                                 bool is_same_page,
+                                 bool is_same_document,
                                  bool is_error_page);
 
   // Adds the |frame_host| to the set of RenderFrameHosts associated with the