Fix uneven padding of network filters in the dev tools.

Also makes the filter bar thinner.

Screenshots: https://imgur.com/a/CClua

First round of reviews here: https://codereview.chromium.org/2105023004

BUG=606897
TEST=open network panel, padding for selected filter (XHR, JS, CSS)
should be even (see screenshots)

Review-Url: https://codereview.chromium.org/2150503002
Cr-Commit-Position: refs/heads/master@{#405154}

AUTHORS

@@ -130,6 +130,7 @@ Craig Schlenter <craig.schlenter@gmail.com>
 Daegyu Lee <na7jun8gi@gmail.com>
 Dai Chunyang <chunyang.dai@intel.com>
 Daiwei Li <daiweili@suitabletech.com>
+Damien Marié <damien@dam.io>
 Dan McCombs <overridex@gmail.com>
 Daniel Bomar <dbdaniel42@gmail.com>
 Daniel Carvalho Liedke <dliedke@gmail.com>

third_party/WebKit/Source/devtools/front_end/ui/filter.css

@@ -30,7 +30,7 @@
 
 .filter-bar {
     background-color: #f3f3f3;
-    padding: 4px 0 4px 0;
+    padding: 2px 0;
     flex: none;
     flex-wrap: wrap;
     align-items: center;
@@ -63,10 +63,10 @@
     display: inline-block;
     flex: none;
     margin: auto 2px;
-    padding: 3px 6px 3px 3px;
+    padding: 3px;
     background: transparent;
     text-shadow: rgba(255, 255, 255, 0.5) 0 1px 0;
-    border-radius: 8px;
+    border-radius: 6px;
     overflow: hidden;
 }