Disable flaky PrerenderBrowserTest tests.

Disables the following flaky tests:
PrerenderBrowserTest.FirstContentfulPaintTimingNoCommit
PrerenderBrowserTest.FirstContentfulPaintHiddenNoCommit

Bug: 832597
Change-Id: Ied5180778c46c29579e6335b638d5758f32e9b45
TBR: droger@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/1012027Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550585}

chrome/browser/prerender/prerender_browsertest.cc

@@ -3287,7 +3287,9 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, ResourcePriorityOverlappingSwap) {
   EXPECT_GT(priority, net::IDLE);
 }
 
-IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, FirstContentfulPaintTimingSimple) {
+// Flaky on chromium.linux/Linux Tests (dbg). https://crbug.com/832597
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
+                       DISABLED_FirstContentfulPaintTimingSimple) {
   GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
   base::SimpleTestTickClock clock;
   OverridePrerenderManagerTimeTicks(&clock);
@@ -3538,8 +3540,9 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, FirstContentfulPaintHidden) {
       "Prerender.websame_PrefetchTTFCP.Warm.Cacheable.Hidden", 1654, 1);
 }
 
+// Flaky on chromium.linux/Linux Tests (dbg). https://crbug.com/832597
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
-                       FirstContentfulPaintHiddenNoCommit) {
+                       DISABLED_FirstContentfulPaintHiddenNoCommit) {
   GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
   base::SimpleTestTickClock clock;
   OverridePrerenderManagerTimeTicks(&clock);