Revert of Combine PDF plugin into the Chromium binary.

Revert of Combine PDF plugin into the Chromium binary. (patchset #17 id:380001 of https://codereview.chromium.org/799643004/)

Reason for revert:
Compile step failed on Official Chrome
See 

http://build.chromium.org/p/chromium.chrome/builders/Google%20Chrome%20Linux%20x64/builds/55563/steps/compile/logs/stdio

ninja: error: 'libpdf.so', needed by 'google-chrome-stable-42.0.2296.0-1.x86_64.rpm', missing and no known rule to make it

Original issue's description:
> Combine PDF plugin into the Chromium binary.
> 
> On Windows, this moves it to chrome_child.dll. Overall binary sizes is 4.5 MB smaller (chrome_child.dll gets 3.6 MB larger while we drop the 8.1 MB pdf.dll). On Mac, the binary is 6.6 MB smaller. On Linux, it's 7MB smaller. This is from official release builds, after stripping on Linux.
> 
> The size savings are because we don't ship duplicate versions of V8, and also the PDF plugin uses some of base and net.
> 
> This depends on OOP PDF, since otherwise the V8 isolates for the plugin and Blink interact badly. That got turned on a few weeks ago.
> 
> BUG=453844
> 
> Committed: https://crrev.com/dc0e4390c0364515fa360c5292a4389784580a48
> Cr-Commit-Position: refs/heads/master@{#314575}

BUG=453844

[kelvinp, 2015-02-04 17:53:32]

Created Revert of Combine PDF plugin into the Chromium binary.

[kelvinp, 2015-02-04 17:53:41]

The CQ bit was unchecked by kelvinp@chromium.org

[bshe, 2015-02-09 14:27:51]

On 2015/02/04 17:53:32, kelvinp wrote:
> Created Revert of Combine PDF plugin into the Chromium binary.

It looks like this is not submitted. No revision number is found and TOT doesn't
include the revert. Is this intentional? Some of the PDF related tests failed
possibly related to the original CL.