Raise timeouts of chrome_public and content_browsertests on android.

From 16 min to 25

Seems to timeout occasionally:
https://build.chromium.org/p/chromium.linux/builders/Android%20Tests/builds/43919
https://build.chromium.org/p/chromium.linux/builders/Android%20Tests/builds/43911
https://build.chromium.org/p/chromium.linux/builders/Android%20Tests/builds/43907
https://build.chromium.org/p/chromium.linux/builders/Android%20Tests%20%28dbg%29/builds/44123

R=jbudorick@chromium.org

Bug: 
Change-Id: I95f1c034c4c5154b44e4cec5df956456ad53eedc
Reviewed-on: https://chromium-review.googlesource.com/580248Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Benjamin Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488426}

testing/buildbot/chromium.linux.json

@@ -364,7 +364,7 @@
               "device_type": "hammerhead"
             }
           ],
-          "hard_timeout": 960,
+          "hard_timeout": 1500,
           "output_links": [
             {
               "link": [
@@ -528,7 +528,7 @@
               "device_type": "hammerhead"
             }
           ],
-          "hard_timeout": 960,
+          "hard_timeout": 1500,
           "output_links": [
             {
               "link": [
@@ -2005,7 +2005,7 @@
               "device_type": "hammerhead"
             }
           ],
-          "hard_timeout": 960,
+          "hard_timeout": 1500,
           "output_links": [
             {
               "link": [
@@ -2170,7 +2170,7 @@
               "device_type": "hammerhead"
             }
           ],
-          "hard_timeout": 960,
+          "hard_timeout": 1500,
           "output_links": [
             {
               "link": [