pdf.js: How the url becomes wrong

1. First, search the keyword with "filetype:pdf book" in google.co.jp.
Now the url says:
https://www.google.co.jp/search?q=filetype%3Apdf+book&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:ja:official&hl=ja&client=firefox-beta
And click the first search result link.

2. Then the first PDF is loaded in the browser window.
The url in the address bar says:
https://developer.apple.com/jp/devcenter/ios/library/documentation/AddressBookProgrammingGuideforiPhone.pdf
This is corect.
Then, click the back button to go back to the search result.

3. Now again, we are back to Google's page.
The url in the address bar says:
https://www.google.co.jp/search?q=filetype%3Apdf+book&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:ja:official&hl=ja&client=firefox-beta
This is corect.
Then, click the second search result link.

4. The second PDF is loaded in the browser window.
The url in the address bar says:
http://web.canon.jp/about/library/pdf/canon_factbook.pdf
This is corect.
Then, click the back button to go back to the search result.

5. Now again, we are back to Google's page.
The url in the address bar says:
https://www.google.co.jp/search?q=filetype%3Apdf+book&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:ja:official&hl=ja&client=firefox-beta
This is corect.
Then, click the third search result link.

6. The third PDF is loaded in the browser window.
The url in the address bar says:
http://www.anicom-pafe.com/book/saigai_techo.pdf
This is corect.
Never click the button in the yellow bar.
Then, click the back button to go back to the search result.

7. Again, we are back to Google's page.
The url in the address bar says:
https://www.google.co.jp/search?q=filetype%3Apdf+book&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:ja:official&hl=ja&client=firefox-beta
This is corect.
Then, click the 4th search result link.

8. The 4th PDF is loaded in the browser window.
The url in the address bar says:
http://ke.kabupro.jp/tsp/20121031/140120121031028097.pdf
This is corect.
Never click the button in the yellow bar.
Then, click the back button to go back to the search result.

9. Again, we are back to Google's page.
The url in the address bar says:
https://www.google.co.jp/search?q=filetype%3Apdf+book&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:ja:official&hl=ja&client=firefox-beta
This is corect.
Then, click the 5th search result link.

10. The 5th PDF is loaded in the browser window.
The url in the address bar says:
http://g-book.com/downloads/startguide/mx_pro/AllPage-mX_Pro.pdf
This is corect.
Never click the button in the yellow bar.
Then, click the back button to go back to the search result.

11. Again, we are back to Google's page.
The url in the address bar says:
https://www.google.co.jp/search?q=filetype%3Apdf+book&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:ja:official&hl=ja&client=firefox-beta
This is corect.
Then, click the 6th search result link.

12. The 6th PDF is loaded in the browser window.
But the url in the address bar says:
http://www.google.co.jp/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&ved=0CEoQFjAF&url=http%3A%2F%2Fwww.olc.co.jp%2Fir%2Fpdf%2Ffactbook2012.pdf&ei=D9YBUeCmEILymAXCuYGgBQ&usg=AFQjCNHC2CgAYiHOfJGEAvo_IdkN2JLUjQ&bvm=bv.41524429,d.dGY
This is wrong.

And once the url becomes wrong, you can not close the yellow bar any more.