Add a gyp flag to allow removing dependency on ppapi.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index f8f2574bedfbefc5e5db62535596f3f0797e6bdc..d3298a34bf35a74ded5d44848598fbdfe241fe56 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -2202,7 +2202,6 @@
             '../cc/cc.gyp:cc',
             '../content/content.gyp:navigation_interception',
             '../net/net.gyp:net_with_v8',
-            '../ppapi/ppapi_internal.gyp:ppapi_ipc',  # For PpapiMsg_LoadPlugin
             '../printing/printing.gyp:printing',
             '../third_party/adobe/flash/flash_player.gyp:flapper_version_h',
             '../third_party/expat/expat.gyp:expat',
@@ -2351,6 +2350,16 @@
             ['include', 'browser/policy/policy_service_stub.h'],
           ],
         }],
+        ['enable_ppapi==1', {
+          'dependencies': [
+            '../ppapi/ppapi_internal.gyp:ppapi_ipc',  # For PpapiMsg_LoadPlugin
+          ],
+        }, {  # enable_ppapi==0
+          'sources/': [
+            ['exclude', '^browser/pepper_'],
+            ['exclude', '^browser/renderer_host/pepper/'],
+          ],
+        }],
         ['safe_browsing==1', {
           'defines': [
             'ENABLE_SAFE_BROWSING',